So since we have a "what keyboard do you use", and a "what audio setup do you have" thread, I figured we should round out with the mouse.
Personally I'm running a G903 wireless right now, and I'm pretty happy with it. The only downside is that it doesn't really have that many usable buttons for me. It's a bit too big to use the central 3 buttons, so I'm left with only the 2 for the thumb and then the normal ones. That said, I like the shape a bit better than the G502 I was using before, even if I do miss the extra buttons (which is why I still have it)