I'm almost embarrassed to say three. I either have a Mini-Grip, Buck 501 or 500 clipped or in a belt pouch, a little Vic Ambassador in my pocket (for the other tools), and a Vic Classic rides on my keychain. The thing is, I like to have a little larger blade just because but the knife I use 99% of the time is the little Ambassador which has a small blade, nailfile, scissors, tweezers, and toothpick.
I have assorted others in my vehicle (I do SAR so ride with rescue gear) including a Fallkniven F1, Buck 119, a couple Farmers and OHT's tucked into my various bags, and a large SAK in the door pocket. Also have a Leatherman Wave in the glovebox.
Still, of everything I own and carry, the Ambassador is what gets used the most.