I just picked up a Victorinox Classic today, so that will be riding on my keys, which go with me everywhere. Also in my pocket, rides a Vic Sportsman II attached by a lanyard to a Maglite Solitaire. This is in addition to whatever other blade(s) I clip to my pockets that day.
My theory is that I can have different layers of EDC...the keychain has a small Swisstech flashlight on it, so if I just need to run to the store or down the road for something, my keys are all I need. Classic covers the knife, and then there's the light. To step it up, I can throw the Sportsman and Maglite combo in my pocket. i find that's also a nice, light combo to have on the odd occasion that I'm wearing gym shorts, instead of something with a belt. Finally, (and this is usually the 'level' to which I am equipped every day), in addition to the Classic, Sportsman, and small lights, go one or two larger folding knives, and a Mini AA Maglite if need be at night.
That means that odds are you'll find me with 3-4 different knives, and at least 2 flashlights on an average day. Oh well...redundancy is nice, eh?