Like Jill, I'm fascinated by the idea behind The Journey to Wild Divine game, an "Inner-Active" computer game, which uses biofeedback rings as a central user interface.
In my dissertation work, I'm working towards an examination of embodied computing in gaming that broadens the reach of the avatar beyond a simple sprite-representation on the screen. You can find some other posts along these lines in the category ergonomics, which is the broad term I use to discuss game hardware and HCI -- see the 6th paragraph of this post if you want a brief description, or see my Level Up proposal, which was accepted (unfortunately, a limited travel budget hindered my ability to attend).
I'd really like to experiment with this (and the P5 glove and PS2 Eyetoy) for my dissertation, but it's just not in the family budget. Has anyone ever had success in requesting 'review copies' of game material for dissertation work? It sure would be nice if I could check it out from the library...
EDIT:
Also check out this article, which briefly describes how researchers manipulated users' bodies by sending small electric currents to alter the balance of the inner ear. [via blog - Pål tænker]