If for voice chat, I use a playstation 2 logitech headset mic setup.
I bought this on clearance at Walmart and is the best headset I've ever used. One headphone, mic, usb adapter and it's easily recognized in windows and os x as a sound source and mic source. So basically I have my voice chat audio route to the headset and game sound go to my regular speakers, and mic goes to the headset.
works great.