From what i found with rammus i always get at least one sunfire cape. It helps with lane pushing, gives decent armor and HP, and does a constant, if small, aoe dmg. Its great for pushing towers when all the creep focus on you b/c of the aoe dmg + tremors allowing your creep to stay alive a bit longer to take the tower down with you. Mind you this is early game, late game if you can't solo a tower on rammus... nuff said imo. But ya cape is a good starting but like most ppl said if its a heavy CC + magic user team against you, get some magic resist of a sort.