twijector

Twijector is a Twitter projector (you see what they've done there?), so you can project the online discussion live whilst a conference or presentation is going on. Your audience can ask questions in real time, and make immediate comments with their mobile devices via twitter, and it will appear in the projected image.  As the blurb says,
a "real-time twitter wall for conferences, events, cafe and classrooms"
Clicking this image should take you to the feed for #tourofbritain