Introduction
Hi everyone, this is a new build I've been trying out, and so far I've been having some hilarious (and successful) results. This is a very non-conventional, but fun, alternative to building 
Malphite as a tank.
My build is subject to change as I experiment with a variety of items.
Why AD Malphite?
It's pretty hilarious. He has a massive AoE gap closing ultimate that lets you wreck people. His W increases his armor and AD by 40% at level 5 while also giving him some great AoE damage. With just a ninja tabi, that means you will have more than 150 armor when you press W at level 18, which makes you ridiculously tanky while building almost only damage items.
On top of that, his Q helps him chase and escape from people, and his E gives an aoe attack speed slow, which means you can gib the enemy AD carry while pounding the **** out of them.
Note: This should not replace your ranged AD carry. Malphite fills a role somewhat like that of Gangplank.
Skill Order
When jungling, the highest priority is to quickly and safely clear to get gold and levels as quickly as possible. To assist you in this, Malphite conveniently has an AOE damage skill called 
Ground Slam that also slows down the attack speed of the minions.
Since you will likely be ganking at level 4, you want to increase your jungling clear time as much as possible by leveling up w and e again before getting 
Seismic Shard at level 4. If you are ganking at level 2, you should get Seismic Shard at level 2 instead, and consider starting with boots instead of cloth armor.
As a top or mid lane champion, Malphite is all about harass. Therefore, you want to max your long range harass ( Seismic Shard as quickly as possible. This will also assist your jungler in ganking your lane, because your lane opponent won't be able to easily escape.
As you transition out of the laning phase, you want to start upgrading your 
Brutal Strikes as much as possible to increase your armor, AoE damage, and AD bonus.
Your ultimate, of course, should be upgraded whenever possible for the higher damage and lower cooldown.
Items
Building 1-2 
Doran's Blades is pretty standard on AD champions, so malphite doesn't really deviate from the norm of an AD champion until he gets a 
Tiamat. Why a Tiamat? Many people regard it as one of the worst items in the game. I like it on Malphite because it synergizes really well with Malphite. The mana regen is great on him, due to his high mana consumption, and the AoE damage synergizes nicely with the passive component of Brutal Strikes. On top of that, it gives 50 AD, which is a very cost-effective source of AD, considering the other benefits Tiamat gives Malphite. If you are jungling, you may consider 
Wriggle's Lantern instead of getting two Doran's Blades. The stats are decent on AD Malphite and the free ward helps you control the map.
For boots, you need to decide what your biggest concern is. If it's CC or magic damage, get 
Mercury's Treads. If it's a fed AD source, go for 
Ninja Tabi. If you are getting fed, go for 
Ionian Boots of Lucidity. The CDR is really nice on malphite.
From there, you probably want to get an 
Infinity Edge unless you're doing poorly. If you're doing poorly (and your team is), get a 
Hexdrinker (to counter fed magic damage) or a 
Glacial Shroud (to counter fed physical damage). You can turn them into 
Maw of Malmortius or 
Frozen Heart immediately or later, depending on the circumstances.
Once you have your Infinity Edge, you will be hitting extremely hard. So, from there, you want to get 
The Bloodthirster for more AD and lifesteal. By this point, most games are nearly over. If the game is dragging out, you want to get some attack speed, and more critical chance, so you can go ahead and get a 
Zeal and turn it into either a 
Trinity Force or 
Phantom Dancer. If the game is dragging out to an hour, you can consider selling your boots to buy a Trinity Force or Phantom Dancer (whichever you didn't get yet)
Results
Fun times were had with critical hits for 1800 damage.
Build Guide
Discussion (5)
Flash: Great for escaping, or flash-> ulting
Ignite: Good kill lane summoner spell. Also good at stopping high spellvamp/lifesteal champs from regenerating as much health.
Heal: Not as good since the recent nerf. Still alright.
Exhaust: It's okay, but you're better off having your jungler/AD carry/support have it.
Clairvoyance: Don't take this summoner spell unless you're supporting. (Kind of goes against the point of this guide)
Clarity: This is a crutch summoner for new players who can't manage their mana.
Cleanse: Not bad to use if the other team has a ton of CC.
Ghost: Good for chasing, escaping, and not getting kited (if you don't have your ultimate).
Promote: No.
Surge: No.
Revive: Don't use this unless you also use 
Teleport. 
Smite: Take this always as a jungler, and never if not the jungler.
