Tritton has come out with surround sound headphones, that include a built-in microphone. These headphones have four drivers in each of ear pieces, used to give the surround sound effect. These look like they would be good for online games.
Unfortunately, these only have a USB interface, so they require a Windows driver installed in order to use them. I would love to see one of these compatible with the PlayStation 2. When I play SOCOM II, I usually wear headphones on top of the headset, so I don't wake the kids or my wife up. This gets pretty uncomfortable after a while. I would love it if someone would make a headphone that integrated a microphone. Then the cable would have two ends. One with a headphone plug to connect to the main sound source, and then another mini jack plug to connect to the headset port.