Interactive public displays are cool. I spent last summer (2007) building software to support a network of touchscreen computers that could sense who was nearby (using bluetooth phone proximity) and react by displaying a collage of social media. Someone made a video of an early prototype:
The three of us wrote a paper about our experiences, called “The Context, Content & Community Collage: Sharing Personal Digital Media in the Physical Workplace”. Joe McCarthy (my summer mentor) will be presenting this work at CSCW in 2008. Read the paper if you’re interested!