Everyone's excited about Sifteo. If you're lucky enough to live in North America you could even order some for a while.
But if you want a little hint at the magical feeling you get from little boxes that seem to know what other little boxes are thinking you could try the much cheaper Boggle Flash. Just one game, just mono, very limited sounds. But you get a real sense of delight from it. It's slightly, but wonderfully, uncanny to see them cooperate and coordinate. A little hint of how a swarm of slightly clever, very connected objects could feel in your life.
(Apologies for the filming, and the poor Boggle. Trying to do both at once proved too much for my brain.)