I’ve offered to help Joi Ito put together a device to be used to send real-time feedback, such as via IRC, to a speaker at a conference using an LED display, like those that display sports scores in a bar. He calls it HeckleBot and he has a wiki page for it. My offer is to provide a small embedded Linux device and software to control the LED sign (in place of a full-sized, loud, power-hungry PC). I haven’t heard back yet.