This is a build that I have been messing around with and been having a lot of fun with. He really is surprisingly good in late game this way. My last game I went 20/6/24.

The problem I have had with other Rammus builds is that I find myself close to worthless on my own later in the game. I tend to be more of a solo player so I had to adjust. This build lets you play Rammus as Rammus, the taunter/disruptor that he is, and later in the game also play him as a viable damage doer, even 1 on 1.

*Updates*

12/30/11: Updated the first build's items, next thing I'm probably going to do is put in a jungle build, I just tried one out and went 25/5/18
12/30/11: Added a jungle build, path and other info on the way. (Just did this again and went 20/3/11, though they did have a player rage quit after my third time ganking him, so I need to test it more fully.
12/30/11: Tried the jungle out for a third time and went 7/0/11 before surrender (and added Proof section).
1/10/12: Changed the name, added builds section and TL;DR section

Pros:

Actually a durable high damage character if even for a short amount of time.
Trollish build
Has over 400 base damage late game (before W even I believe)
Deals nice crits
Very fast movement speed for the majority of the game
Nice disrupts constantly.

Cons:

No life steal until the last item of your build and it is situational only.
If you do choose life steal you will be slow as can be without your powerball active.
People will expect you to be a tank
Probably won't get you top score in a ranked game

Your Runes and Masteries are chosen to help you survive. Your items and the general Rammus character should help you do a fair amount of damage. Greater Seal of Armor flat runes help your character do more damage at the beginning where as your Greater Glyph of Scaling Magic Resist runes should help you survive at the end-game when you are more susceptible to magic users.

Recommended:

Exhaust: Primarily for early game as you will be more of an assistant to begin with. Also good since you may be the only person on your team to be able to catch up with a champion, allows teammates to catch up.

Teleport: Good for easily replacing your items and helping out allies/ganking. You can even start your Powerball beforehand to really surprise them.

Flash: Good for using Powerball then flashing over their minions to slow them without them expecting you. You can go over walls even, that is always good.

Other Summoner spells:

Ghost: Alright spell, it makes you go faster, but so does your Powerball. If you are going to get ghost, just get Flash instead and use Powerball along with it to escape. Then at least you can go over walls or minions.

Smite: Use if you are going to jungle at the beginning only. In which case I would get Cloth Armor first with 5 Health Potion which you will turn into Thornmail and work around from there.

Ignite: Always a fair choice, good for escaping people when your damage isn't that great yet or those darn tanks that have too much armor.

None of these builds should really be done if you are the main tank unless you are winning by a whole lot.

With that being said:

Build 1:

This is a basic build if they do not have any good AP, your job is to run in and taunt one of their strongest damaging champions, if they are AP, they will not be using it as long as they are taunted, if you can get the team to focus then they should be dead before your taunt is finished. (or if you are fed enough)

Build 2:

If you keep getting rocked by AP champions then this build may be more useful to you. This build doesn't have Bloodthirster because with both Warmog's Armor and Force of Nature you should have some insane health regeneration.

Build 3:

Standard Jungle build that turns into build 1. You can of course switch it to be more like build two if needed.

You will start out playing as the typical Rammus build, assisting whenever you can initiating with Powerball and taunting to help your teammates get kills. Due to your fast speed you are also very viable when it comes to ganking others.

Later in the game you should be able to initiate against any squishier target and solo them. Whether they are AD or AP due to your Puncturing Taunt and Defensive Ball Curl and quick initiate with Powerball.

Late game you will want to enter the fight right after the tank. Try and disrupt any carries and Puncturing Taunt/ Defensive Ball Curl them. You have to remember that you will be vulnerable when your W is not activated. Keep up whenever possible.

If you seem to be losing life too quickly when you Puncturing Taunt/ Defensive Ball Curl earlier in the game then pick up another stack of Defensive Ball Curl earlier in your leveling sequence. You would be surprised how much it helps both your survivability and your damage from the extra armor!

Remember that you will be vulnerable against AP carries, mostly when you have your W down. Try and avoid a 1v1 against AP characters/hybrids with an excess of life such as Jax.

NEVER FORGET YOUR Defensive Ball Curl!

This isn't your typical build, you should see that already. Items are self-explanatory, Armor helps you survive/helps your attack due to your passive.

I have two separate builds shown, the second one much more viable than the first as it has more MR and Armor. For the first build it might be a better idea to replace your Boots of Swiftness with a phantom dancers instead of Bloodthirster in most games. Having Bloodthirster is very much situational if their champions aren't great at escapes, or if you don't have anyone to get dragon.

Try and sell your Heart of Gold as late as possible for the extra gold and life that it gives you. it may not seem like much, but that gold adds up and it is always good to have a little bit of extra life towards the beginning of any game, especially when you are focusing on your puncturing taunt ability.

Powerball:

Don't forget all of the things that you can do with powerball active. You can Flash with it to jump over minions or a wall. You can Teleport with it on you.

Always let your powerball charge at least for a little bit before initiating as it will increase your speed gradually. (longer powerball is active=faster you are=less response time for them to escape.


Tower diving:

Don't forget, you are Rammus, when you use Defensive Ball Curl you have a fair amount of armor especially stacked with your Thornmail. You can take a couple of hits from the turret. Just watch your W buff, it wears off and you start to really get hit! But chances are, better you than one of your squishier teammates.

If your team doesn't have a tank, don't do this build.

If you are getting facerolled by AP: Get Force of Nature

If you are getting facerolled by one or more fed ADs: Get Thornmail. You can kill a fed Master Yi with a Puncturing Taunt and Defensive Ball Curl

Use Defensive Ball Curl often. Same with puncturing taunt

You are not a tank, you are tanklike for only a couple seconds. Don't initiate against a whole team, it doesn't end well. If they suck you can kill 2 and get away, (done it when they weren't expecting it), but that was due to lack of CC/intelligence.

This build requires quite a bit of gold and is focused more on late game activity. Many builds are situational, that should always be taken into account. Know your champion no matter who you are. Keep map awareness and don't be afraid of ganking. You are fast and you can help teammates dominate their lanes very easily.

End game you can solo Baron, I don't suggest it unless you have a whole lot of time to yourself or if you didn't have to make yourself tanklike at all. I've soloed Baron as my entire team sat around me and watched to see if I could do it, fun stuff.

This is a build I have played a couple of games with and they were really fun. Try it out for yourself and send me some feedback, I'd love to know what you think. Have fun and God bless.