Yahoo's latest brain-child is, well, a giant brain, which doubles as a two-story terrarium atop the Hard Rock Cafe in New York. The PR stunt is meant to promote Yahoo Answers, an online community where consumers ask and answer questions on any topic, writes Promo Magazine (via MediaBuyerPlanner). Within the terrarium are 22 "brainiacs," picked from an online submission process, who are answering questions from Yahoo Answer users.

The website includes videos of events taking place at "the brain" and a live feed, along with Flickr photos from visitors and sample questions the brainiacs have answered ("Should I start my kids on skiing or snowboarding first?" "Can anyone please explain how to watch golf on TV and enjoy it?").

Visitors viewing the brain can stop by a kiosk across the way to use PCs in order to ask or answer questions on the website. Or, they can visit Yahoo.com to view a live brainiacs webcast. A microsite will be announced "soon" on which consumers can pick animated characters that will act out their questions and which can be sent in messages to family and friends.

Print ads in USA Today, radio ads and banner ads across all of Yahoo products support the campaign. Yahoo's Buzz Marketing team is handling the Times Square event. Yahoo is known for some of its publicity stunts, such as once creating "the world's largest snowglobe" to promote Yahoo Shopping.