What kind of models would be good to start with for simple 3d-games? What I need is something that is easy to understand but looks pretty good, say for monsters or something in a rpg game. I found some tutorials and was able to get a quake 3 model into my application but it didn’t feel right since I didn’t understand much of the code.

If not MD3 then try MD2 - no skeletal animation, quaternions etc., morphing animation only.