Look into some Bongos, cowbell(a couple sizes), tamborine(get a good one with a head on it as you can do so much more with a real tamborine compared to a basic one), shakers, maracas, claves, congas. It kinda depends of all you want to do but start off with some of the above and then just add on as you like.
Other things that are fun are roto toms, guierllo (spelling), triangles (2 or 3 sizes are always nice), slap stick, dijeredoo, wind chimes (you can make one if you can get ahold of about 50 or so old keys, if interested let me know and I can tell you how to make), steel drums, slide whistle ect ect.
Percussion is such a broad subject you could get lost in it for a while. Get the basics and just grow as you learn how to use each one differently.
Let me know if interested in the homemade wind chimes.
jontflesh