I have two keychains. One has my home and car keys on it, the other has keys to a couple of things at church. I don't particularly need the keys with me but having had a couple of occasions where I couldn't find the keys where they were supposed to be I asked the pastor if he had a problem with me having my own copies, and he gave me the OK.
Sometimes I have something small on a keychain, like a souvenir keyfob or bottle opener or similar. Usually it's just keys. I typically don't want my keys to be too bulky because I like to be able to put them in a pocket.