Wii Voicechat -- Howto
The idea is to use a bluetooth headset on your PC while playing on your Wii. With online games like MOHH2, BWii, and maybe SSBB just around the corner, you may want to have organized teamplay, or just taunt your competitors. Free VOIP programs that will let you do this are listed and discussed at the link above.
Alternatively, if you have a laptop with wifi, you wouldn't even need a bluetooth headset to make it work. Just bring your laptop into the rec room, plug in a wired headset/mic, and go. It's not ideal, but I'll bet there will be people doing it so they don't have to lay out the dough on bluetooth.