I really liked StreamDialog( http://twitter.com/#!/streamdialog ) - good pitch, nice idea, simple product and i was suprised with their end-result and partnership with vkontakt.ru (russian facebook), and all happens in 12weeks.

I think, BusFaster ( http://www.youtube.com/watch?v=_Xzvm6IOk1g&feature=playe... )is perfect example how to kill real pain.