I try to keep it at a minimum with my key chains. I don't like to carry too many stuffs on the key chains because sometime it is a hassle for me to try to fumble to find the right key to use to start the car, open the house door, so and on.
Anyway, On my key chain, I have a carabiner (it is a metallic loop w/ a gate that people use for rock-climbing), 2 plastic key cards (for Kroger and to the local gym) and a novelty keychain that says "I'm not as innocent as I look." And also, of course the car/house keys as well.