Not too long ago I found this awesome US Army Radio Headset from the Vietnam War. It was still in the box unused (I think)! I thought it would be fun if I could use them with X-Box Live.
It was a simple mod. The headset has two plugs (for earphone, and mic), I took a spare molex cable from a PC power supply and connected the prongs, they fit perfectly! Everything worked pretty well as is, the microphone has a bit of static when you speak on XBL so I may open that up and replace it with a more modern one.
Click the last image for a closer look of the headset, its build to last!