In every team there should consist of 1 Capper, 3 Attackers, and 1 Defender (usually bot). Now out of all the Cappers people have said Shaco, Eve, Rammus, and Janna r the best. I have to admit that is somewhat wrong. ALL Cappers r good depending on how u play them but there is also a problem of u dying when playing as a Capper. Janna is probably the most superior Capper by far in this game in my opinion; however, Zilean is the secret BEAST that not a lot of people use. First good thing about him, he has a speed boost and a slow for the enemy chasing you. Second, he has an ult that helps u not to die and also when ur with teammates that r about to die you just ult and they back alive. Third, his Rewind pretty much makes you able to spam skills crazily all game long.

Pros:
so fast they cant catch you
the other team will get annoyed by you which makes them make mistakes
slow???? i forgot wat that was....
Cap Cap Cap?!?!?! o we have more points that you :P

Cons:
no dmg watsoever
easy to kill if they stun, snare, taunt you (slow doesn't really work on you)
your no help if they have 2 Defenders...

I use 0-9-21 to try to get Zil to be as fast as possible. You may use a more tanky version but if your getting hit a lot from the enemy then your playing him wrong. You should be kiting and escaping (even by a hair) just to survive.

My Item build yes... it does work but you can try a different version which i saw a lot of rammus people use:
Boots of Mobility
Priscilla's Blessing
Phantom Dancer (x4)

I really hate this build since Phantom Dancers r really pointless besides their speed boost so i try to use the least of them as possible (as you can see i only make two of them and only after i made everything else first)

Ghost is a MUST!!!! If your not using it as a Capper then that is just plain wrong. It helps you run faster thru the jungle to get to a cap point!

Revive is a meh... you dont really really need it but i find sometimes i will either never die in a match, or i will die once or twice in dominion.... but BAM! revive... i've back alive with the speed boost and i'm running so fast to the other team's bast and i just capped a point :D

Cleanse is another spell i see arguable with Revive. its either Revive or Cleanse. Cleanse removes all debuff besides suppression which is awesome so i guess this makes it viable. really... its your choice :D

First thing I usually do is go for either the drill or refinery depending on the team. after that then i head straight for the other teams refinery or drill. from here on out its just how you can maneuver around ur enemies and when to cap.

p.s. your goal is to cap as much as possible... dont think of helping your team in fights too much since your no real asset except for you slow/speed and ult