Here's a cool thing—a Twitter-powered billboard from Jell-O Pudding.  It's essentially an outdoor version of the Jell-O Pudding Face website  we wrote about earlier, which monitors the mood of the world based on the number of smiley- and sad-face emoticons posted to Twitter. (Whenever overall smileyness dips below 50 percent, the brand gives out coupons to the randomly downcast.) The billboard, from Crispin Porter + Bogusky, went up on Thursday and sits at the corner of West Broadway and Grand in New York City. Interesting to see an out-of-home ad responding in real time to the social Web. Via The Denver Egotist. 
UPDATE: Check out this hilarious video  in which the man whose face was used for the ad—former CP+B copywriter Ian Hart—sees the billboard for the first time, having not known it was planned.