I'm probably forgetting a bunch of stuff, but here's what I'm bringing to Uganda:
Proof of yellow fever vaccine (required for visa entry).
Malarone pills (malaria).
New $100 bills (apparently these have a better exchange rate).
Digital recorder (for interviews).
Binoculars (for bird-watching and other animals).
Notepads and pens (as gifts for kids).
Sneakers (for tracking gorillas).
Guidebook (with key phrases).