I really hope this Lego Cuusoo FTL set gets approved.
This Lego Green Lantern Power Battery may be the best thing ever (at least for this week). This would be amazing as-is, but the creator of this at JustJon.Net hit it out of the park by a) making the battery actually light up, and b) having the light triggered by an RFID-equipped ring.
This chess board built with Lego Mindstorms is amazing. The group that built it has lots of information about more information about building this on their website.