This guy has used the sixaxis, glovepie and some other stuff to show how it's pretty well possible to do what I've always thought would be possible for FPS games, using the sixaxis! I particularly like the second video, though in theory his 3d glasses application should probably be more impressive in real life. 
http://joelclemens.colinr.ca/stuff.html
http://joelclemens.colinr.ca/stuff.html
