Usually just two: a Leatherman Wave on my belt and a small SAK (a Wenger "Classic') on my key chain. I'll occasionally supplement these with a Spyderco Endura if I know I'm going to traveling through somewhat 'questionable' areas.

I'm still looking to replace the SAK with something a little more versatile; especially now that it's primary function (scissors) has been supplanted by the Wave. I may look at a slightly bigger SAK or perhaps a Leatherman S4 Squirt.

I bought a Buck 'Minibuck' tool in a moment of weakness, thinking that it might replace the SAK. What a piece of garbage that was!