A 29er... I'm thinking Kona Unit 2-9 or a Rig. I've already got three singlespeeds but they're each set up very differently from one another. I'd like a 29er because it would also be completely different than anything else I already ride, and I think I'd like those big wheels better than anything.
But heck, as long as this is a WISH LIST... what I REALLY want is a new Vulture 29er decked out with nuthin' but the best components. As long as I'm wishing, why not make it custom and blinged out to the max?