I carry a Kershaw Lee Williams design black Ener-G Kickstop flipper at work. It is small and unobtrusive, it blends in well with my navy colored scrubs, and it opens easily and very fast. Plus, since it is an inexpensive production knife (about $50 street price new), I don't worry about accidentally losing it.
Today a Spyderco Endura 4 and a Leatherman Squirt S4. Lights include a SureFire A2 and a couple of coin-cell lights with my keys. (One has an ultra-violet LED.)
The bag in my drawer adds a Boker Plus Trance and a Byrd Robin. (I swap the Endura for the Robin when I need to step onto a school campus.) Lights include a Streamlight Stylus (3 x AAA) and Sgt. Burkett (Korean semi-custom).
Some of you have already seen it in the slipjoint thread in Custom Knives, but that's okay, I suppose. My EDC knife is this Colonial jack knife--it's a little cleaner and sharper now, but don't worry, I only used steel wool and very fine grit sandpaper to clean the gunk--no reprofiling here, folks!