Thorn Mail and Sunfire cape seem pretty well "built" for Rammus. Force them to stand near you and hit you while you burn their face off and reflect enough damage to make anyone cry. Thorn Mail is getting a bit of a buff in the upcoming patch also, so that should make it even better for him. Guardian Angel also can be a good idea for Rammus.

Other than that you should consider picking up an Aegis for your team. Between those items you'll have all the armor gear you'll ever want.

frozen heart is also great, he has very low mana, and the ring will double it, and with 4 active spells, the cooldown reduction works wonders

the problem isnt that there are no items for him, its that there is not much variety in builds for him

Thats true for most tanks, thier usually exaclly the same, only slight diffrences based on the opposing teams make-up

You have to figure out what kind of wall you want to be. I think HP stacking for tanks is foolish considering that bloodrazors are in the game and tanks don't get innate MR increase. I almost always look for a mix of MR with either armor or hp. Everyone has abilities. MR is probably the best tank stat in the game unless you are going against a ton of carries.

If you run into that than get thornmail or sunfire capes. At least you will do something to them before they cut you to pieces. Dodge goes a long way, but that is more to do with runes and masteries considering you aren't going to want a phantom dancer. Nor can you afford it.

I honestly have no idea where OP is coming from.

Early on you can pick up a Doran's Shield, which does HP, Armor, AND HP/5. Middle levels, you grab a couple of Heart of Golds for the HP, Armor, and money along with your boots, which become either ninja tabi or merc treads based on your opponents. Then start picking up high tier Armor items. Frozen Heart, Thornmail, Sunfire Cape, Guardian Angel, Warden's Mail are all good options.