This is my build for Wukong The Monkey King. He's very maneuverable with great damage output and quite capable at farming as well. I've yet to fight a Wukong who was better than me. Very fun and effective build. Enjoy!

Pros:
Very tanky early game
High armor penetration and damage output
Decoy can put your enemy's abilities on cooldown wasteing their mana, ults and summoner spells.

Cons:
High cooldowns at low levels
Mana dissapears very fast at low levels
No stun/snare/slow

Greater Mark of Desolation and Greater Quintessence of Desolation with Sunder will give you a flat 31 armor pen right off the start, what this means is that some champions will be negative armor to you, makeing you do tremendous amounts of damage to them early game, later in game your Crushing Blow removes 30% of armor, which will add more overall armor penetration.
Greater Seal of Armor and Greater Glyph of Magic Resist will make you almost invincible with your Resistance , Hardiness and Stone Skin passive.

21 in offensive why? cause this is a D/s build, I've tried both defensive and offensive and I believe offensive will help you more in this particular build anyhow.
6 in defensive to make you a boss and 3 in utility, Perseverence I feel that however small the difference this may make, it may be the difference between escapeing with your Warrior Trickster or getting a kill with your Nimbus Strike. I have not actually checked what the actual numbers are but I do know if its 1 mana or 2 mana per 5, there is 12 ticks in a minute and 24 ticks in 2 minutes, that may be just what you need. Plus the health regen % synergy with your beast defense and Doran's Shield is very nice too.

excellent starting item - will give you a buttload more sustenance.
getting the tier 2 boots straight off will help you maneuver your skill sequence's and increase your farming capability.
movement speed will help you survive and kill, attack speed and crit will help you farm and kill.
once you get this it becomes easier to chase people down, your Zeal, Berserker's Greaves will increase the proc chance.
keeping up with your sustenance, increasing damage output and farming ability.
adds sustenance and damage but also allows you to slow your opponents, is very nice!
Nom Nom more damage!
more movement speed and increased damage output through attack speed and critical strike.
more damage, critical strike and critical damage. >.>

The last Item.
At any point after B.F. Sword you can trade in your Doran's Shield to progress in the item build. the last item is purely situational, whatever you need. If it's a balanced team of 2 AP 2 AD I'll get Banshee's Veil for magic resistance and anti-cc, perhaps you might like another Phantom Dancer or Bloodthirster or even a Atma's Impaler, it's up to you to decide what you need most against the enemy team composition.

, , , , , , is what will usually be your maximum damage output skill sequence. though during team fights you can , then , , , , useing Ignite during Cyclone or after the skill sequence.

To harass, , , but when you are winning you can just , and save Warrior Trickster so you have more mana to repeat this. Early game this is expensive so use it sparingly and when your partner attacks, attack with him in this sequence saving Warrior Trickster for if you are targeted.

If you are losing in your lane, on minions for farm and immediately and back off, ask for help in your lane or Recall instead of giving them a kill. If your tower dies just know that you did your best and after healing immediately head out to continue farming gold sauce, dieing in nearly every case wont save the turret.

can get you kills, a surprise ult initiation or save your life when/if someone does not fall for the decoy and waits for you to resurface. must have!

can get you kills if the enemy can retreat after you've gotten him low enough, or force back opponents who pose a threat to you during laneing phase.

can also be a good second summoner spell as it can reduce someones ult damage on you or a team mate by 35% or slow a enemy so they can't retreat and score a kill on them.

As always try to last hit as much as possible but also with this build we max out Nimbus Strike straight away so this can be a great tool for farming, used when there are multiple units with low hp, however keep in mind that he has some mana issues early game so to account for his mana issues early on don't farm with nimbus strike if your low on mana incase, I wouldn't waste the crushing blow for minnion kills early game It's a waste of Mana, save it to harass and kill. don't waste mana on decoy it is only used when you are about to be hit by abilities.

Wukong is a great assassin with a gap closer, armor pen and increased attack speed he can do alot of damage his only cc is his knockup ult, but a Frozen Mallet fits right into this, coupled with a Phantom Dancer for increased move speed, you can chase down enemies pretty easily, decoy past his team and nimbus strike crushing blow again to kill and juke your way out through the jungle, great for killing squishy carries. His ult is great in a team fight also, bringing cc and aoe physical damage to the table can definitely win your team fights if used properly, although sometimes I find nimbus strike too slow to catch an entire team in your ult so useing flash can actually help you hit your cc off on more targets quicker, Wukong is very fun and definatly worth a try, but he may take some getting used to in terms of where, when and how often to use his abilities. From my personal experience with Wukong if he is fed early game he will be monstrous, his gap closer with high damage slow knock up armor pen crit build he is deadly even to tanks. He isn't as good solo lane, he has mana problems early on, nothing he can spam, so auto attacking and harassing once in a while with his e and q to hopefully get a kill, flash ignite are great tools to try to get early kills. the early zeal and eventually phantom dancer, I cannot express how good it is to have the extra move speed boost, it's only 15% but it's sooo good, I say screw trinity force, get Frozen Mallet and Phantom Dancer instead. once you get your wriggles farming creeps and jungling becomes alot easier especially with the attack speed from Nimbus Strike and your zeal.
So just to summarize what this item build offers:
Movement Speed/Attack Damage/Attack Speed/Critical Strike/Health/Armor/Magic Resist/Life Steal/Slow on Attack/Spell Block-45sec/20% 500dmg proc on creeps.

Have Fun and Pwn Face!