For clogs that aren't too far down (like in the trap) this thing really works:
http://www.amazon.com/Cobra-Products...s=drain+snakes
The teeth grab chunks of the gunk and draw it out rather than trying to shove the whole thing deeper. They are also all of a couple bucks at the local hardware store. Since they are so cheap, you can just toss 'em if they get too gross.