A Mac and Bluetooth.
I wish I had these. There's a very interesting application called Salling Clicker that Paolo wrote about - when his Sony Ericsson phone rings, he can see who is calling him on his Mac's monitor. he can control many applications via the phone. He can have his music pause when he leaves the room. Automatically. And have it turn back on when he comes in the room. Automatically. That's what I need.