I'm currently working on my EDC keyring. I already have a compass and flashlight on there. The el cheapo zipper-pull style compass is being upgraded to a Brunton 12NL one and the flashlight was just upgraded from a Maglight Solitaire (1 hour runtime) to a Inova Microlight (15 hour runtime).

My mini Fox 40 whistle and Bison Designs keychain capsule will be here in a few days. I'm thinking on keeping the keychain capsule on the keyring also with a few waterproof matches in it.

So on my keychain alone, I'd have fire, whistle, compass, and a flashlight. And I keep my pocket knife clipped in the same pocket as the keychain. One pocket, much usefulness, very quick to access everything when you need it, even with your eyes closed.