Sure --
The Astro Mixamp is a dolby digital decoder/amplifier for headphones which is geared towards gaming. It takes two audio sources (your game sound and the voice chat) and allows you to mix them together quickly and easily. It is mainly geared towards XBox/PS3 (where you don't have a sound properties menu to tweak those two things) but also works great on the PC. Here is a picture of the wireless one that I use, there is also a wired version.
The USB cable that I was waiting on allows the Mixamp to be a second sound card on your pc, to enable the voice chat and mixing of voice/game chat within the device.
The final piece of the puzzle is a software program called Ventrilo. It is simply a gamer based chat program where as many as a couple hundred people can be in a room and talk to each other.
Putting it all together I have a near wireless headset (there is a cord going to the mixamp receiver, but I am not tethered to my desk) with amazing sound that I can dial in the perfect amount of chatter from my teammates.