Ok wow! So much has changed with the Sept. Patch. For one thing Crisis all but declared for everyone that 'BurgandyLantern was right this whole time!! ; )' Anyway, all his moves scale off AD now and his heal scales off max health so the game has changed, Aqua is going to be so much stronger and harder to kill now. I'll make a proper update to this guide when I can.
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Update December, 2014

Aquaman is still basically the same except now he is much easier to build for.

Skill Order: same as before. The reasons I listed below still apply.

Item Build:
Just buy the Health and AD items. They make you tanky and still deal damage.
1. Claw Of Horus (3)
2. [[Lobo's Chain (3)]]

I buy a [[Doctor Destiny's Dreamstone (2)]] so I can spam my skills.

And then you're done. Once you have those three items you just build AD if your dominating or defense if you're dieing. Being the king is just too easy.
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Why AD?
 
Hahaha! SooOOo many reasons! First and foremost is that a PD Aquaman is a poke champion. Poke champions safely whittle down their enemies from long range and only go in when the opponent is at a clear health disadvantage. Ergo; poke champions are punk bitches. Aquaman is no punk bitch; he is a freakin’ king.

Secondly, his passive heals for 20% of bonus AD, basic attacks obviously scale with AD and you can proc this incredibly quickly with a Stagger (W) and double Undertow (E). This synergy makes AD Aquaman an incredibly potent duelist.

Thirdly, 2 basic skills and 3 Ult variations are close range abilities and when you are in melee range you want Attack Damage. Trust me. I write guides.

Finally, and probably most importantly, when there are two Aquamans (Aquamen?) battling to determine the one true King of Atlantis; A PD Aquaman will always run from an AD Aquaman. Always. It is simply the PD play-style, please refer to my first point if you don’t believe me.

Important!
When following this guide there will be many fights where your health drops scary low. During these times it is important to remember that you are stacking Life Steal and therefore turning on your opponent is actually the safest thing to do in several situations. Once you can gauge the squishiness of your opponent and your own squishiness, you can come out on top of some very bleak situations.

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Modifiers and Amplifiers
For mods take:
1. Enhanced [[Shade's Cane (2)]]: This adds +9 AD starting at tier 2. Shade's Cane is a core item for AD Aqua because it boosts all his damages and continues boosting the more Auto Attacks you do.

2. Enhanced [[Doctor Destiny's Dreamstone (4)]]: This mod now gives Power Armor. Not that great anymore but I grab this item every game because it eliminates will issue and gives a lot of cooldown, so having some free stats on top of that isn't too bad.

3. Accelerated Soultaker Katana (4): This mod gives 2 stacks per coin. After the last patch, this item now takes 60 stacks to reach max value. If you want to use the Soultaker Katana, you need this Accelerated mod.

For Amplifiers I focus on Attack Damage, Life Steal and Armor. I specifically take:
1. Kord: Diver [+.25 AD per lvl] [+1% life steal]
2. Kord: Chilly [+1% life steal] [+18.5 health]
3. Wayne: Monster [+3.25 Attack Armor] [+1.44 Attack Speed]
4. Wayne: Cliff [+3.25 Attack Armor] [+3.25 Power Armor]
This combo gives me a strong early dueling potential that suprises most enemies and lets me all in most champs at lvl 2 pretty successfully with just a (Q) > AA > (E) > AA > (E) > AA. The 'Rising Tide' empowered Auto Attacks gives good burst and great sustain for the early fights.

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Stolen Powers
In Lane
[[Doomsday's Invulnerability]] and [[Arcane Green Lantern's Healing Wave]]:
 These are the Stolen Powers to take in order to massively increase tankiness. You will be in your enemies face and probably in the middle of the enemy team in many situations so these are a great advantage in both team and 1v1 fights.

Jungling
[[Joker's Detonate]]
  Another great thing about AD Aqua is that you can clear jungle camps quickly and still have that innate sustain. When Jungling I like to grab detonate for faster clears and less damage from small creeps, who usually die immediately after a detonate.
[[Atomic Green Lantern's Consume]]
  Another Stolen Power option when jungling. When you have this kill the smaller creatures first then move on to the big one. Using consume near the end of the fight to maximize health after a clear. This power has a higher true damage but doesn't have the AOE of detonate.

AD Aqua can handle jungle camps quite well on his own, I have even done it with without the standard Jungle detonate/consume combo. The stolen powers are up to personal preference really, I have fun with detonate and super speed/ x-ray vision for ganks or healing waves for better tankiness and team-fights.

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Items

Start with Aquaman's core item [[Shade's Cane (3)]]. It is a powerful hybrid item that buffs all of Aqua's skills and it grants even more power on repeated basic attacks. It is one of the cheapest items in this build for the power it provides and you should easily be able to buy the lower tiers while still in lane.

I then pickup a [[Doctor Destiny's Dreamstone (2)]] because it is a cheap item that completely eliminates will issues.

Follow this with Soultaker Katana (3) so that you have precious life steal. If you got the Accelerated Mod you will have max stacks in no time. And of course the extra AD naturally fuels Aqua's sustain.

After that get [[Joe Chill's Revolver (1)]] ASAP. Joe Chills is massive on AD Aquaman because it gives a big power spike and heal spike from Rising Tide.

The idea after this is to stack more and more AD. Attack speed is not that crucial on Aqua because what we are really focusing on is the combined burst and sustain from his passive which only procs after a skill use making subsequent, non Rising Tide empowered attacks less important. With this in mind, I have had some success picking up Psi-Scimitar (3) as a late item because it synergizes perfectly with the Rising Tide proc once you have a lot of base AD. Though after the patch, I rarely grab the scimitar and instead lean towards Tanky items which have proven even more powerful because they let you stay in the fight longer to dish out more basic attack damage.

Also following this idea Sword Of Beowulf (3) and Claw Of Horus (3) are powerful defensive items that give Armor and Attack Damage to further buff Aqua's life steal.

The above order is a good start but as always item builds are completely situational and it is important to buy with the intent of countering your lane opponent and then the Enemy team in general.

So as defense Items go Suit Of Sorrows (4) and [[Mirror Master's Prism (4)]] are great picks when against AD/AP focused teams. [[Ra's al Ghul's Robe (2)]] is another great choice that covers both Attack Armor and Power Armor. As AD Aquman a lot of your defense will be in the form of sustain/ life steal but you should get a defense item because you will be in your enemies face and close to their team.

Optional Items
Ok, that rant is over. A TL;DR version of this is to make sure to grab [[Doctor Destiny's Dreamstone (4)]], [[Shade's Cane (3)]], Soultaker Katana (4), [[Joe Chill's Revolver (4)]]  and an appropriate defensive item. These 5 items are the core build we are aiming towards in this guide and once achieved you will be a scary, in-your-face brawler.

But this leaves open a whole item slot where we can put whatever we want! As you can probably guess, I'm going to suggest even more Attack items.

1. [[Huntress' Crossbow (3)]] : this gets you a nice AD boost and a 15% cooldown reduction. Combined with a max Dreamstone, you will have 35% cooldown reduction which puts Undertow (E) at 5.89 CD and your ult at 13.65 seconds. More Skills = More Rising Tide = More Fun/damage/healing.

2. [[Deathstroke's Claymore (2)]] : AD and AS bonus. Grab this when Shazam, Mecha Superman and GasLight Joker try to bulk up on HP. The annoying mass of fat won't know what hit them.

3. Atomic Axe (2) : If you have been having a good game so far, the enemy has likely bought Attack Armor out of respect-fear. This handy Attack Penetration effectively squashes their dreams.

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Abilities
Rising Tide:
An incredibly powerful passive that lets you both sustain and burst enemies after skill use. Make sure to land an auto-attack after each skill, it will greatly improve your DPS and sustain. It is the only reason I gave AD Aqua a try and it is the reason it works. Max it 2nd. Your enemies will learn to fear the rising tide.

Trident of the King (Q):
Fun skill shot that has powerful scalings and it even grows in power as your enemies run from you. Hilarious. I put an early point in this skill so that I can harrass the enemy champ and then easily last hit and sustain on a nearby drone. You can level this last because the cool down never changes but the cost goes up. This makes Trident super spammable and a low cost initiation once you hit lvl 6. It has a low cooldown so make sure you use it whenever it is up during a fight, even at close range. This will proc another Rising Tide and give you crucial healing.

Stagger (W):
A knockdown utility skill that gaurantees a proc of Rising Tide and can knock enemy champs out of ultimates and channeled abilities. Very useful. We get this at lvl 3 and max it 3rd because the knockdown duration increases per lvl

Undertow (E):
This skill is great. It lets you reposition, chase, escape, clear drone waves and melt champs. It can even be used a second time at no cost! Each use also pretty much gaurantees a proc of Rising Tide. We max this first. The reason I level Rising Tide after every point in Undertow is because your DPS will actually improve when you proc a stronger Rising Tide off all your skills instead of just front loading a skill and then rushing the passive.

Might of Atlantis (R):
A transforming Ult that is very fun to use and very versitile. It also has a very short cooldown so feel free to use it constantly.

Surge: It activates after hitting your Trident of the King and has a huge range. This is most useful for intiating as it closes the gap from a huge distance. Follow this up with a Stagger(W) and you should be able to get off a full combo with no problem. It also scales off 100% of your Bonus AD which is just beautiful. In raw numbers it is your most damaging Ultimate and it has mixed damage making it difficult to defend against.

Wrath: A very satisfying execute that works off missing health. It is all power damage though so it is relatively weak in this build. Fun to use but pretty situational, I only really get kills with this when an enemy is so low that I probably didn't even need the ult. The animation is worth it though.

Capsize: A powerful move that does respectable damage and lets you repostion an opponent. Use it to secure a kill or to throw an enemy away from you as you escape.

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Laning
Early Game:
Be very aggressive. As you wait for last hit chances move around and harass with your Trident. This is incredibly effective if you can consistently hit your opponent because you can safely attack a nearby drone for more health after applying a large chunk of damage to your enemy. This tactic is especially powerful combined with the current meta because many people will buy power armor to counter you. This is a mistake that will cost them their lives. Once you hit level two grab your Undertow and look for a chance to get close to your opponent. Your early power is very strong and your opponent will stick around because they underestimate the heals coming from the Rising Tide. Also at the lower levels your chance of getting ganked is very low so have no fear and farm that champion!

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General Tactics
1. When using Undertow (E), you have 4 seconds to reuse the skill. Tactically use this time window to dodge skill shots and put the enemy off balance. You can play some good mind games by switching your timing of the second use. If you manage to dodge a skill shot or an ultimate with a big windup (GasLight Batman, Cyborg); your enemies will start to try to wait for you to use the 2nd Undertow so that they won't waste their precious skill shot. If you notice this happening just laugh and beat on them while waiting until the last possible second to reactivate the skill. Their DPS will go down when they aren't sure when to use their skills.

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