I've been thinking you could hook up a cam/mic to one of those Roomba vacuum 'bots and then you could cruise around the conference and network with your colleagues just as though you were there. I understand those things have wifi already, so....
The coolest part would be bumping into other Roombas that represent colleagues from elsewhere (you'd need a way to distinguish from an ordinary, autonomous Roomba). There could even be a Roomba room just for them!
Someone did this a while back -- it made HN, but I don't remember who was behind it. It had a camera and an LCD display and could travel between offices and conference rooms in an office building several states away, attending meetings and generally hanging out with coworkers.
The coolest part would be bumping into other Roombas that represent colleagues from elsewhere (you'd need a way to distinguish from an ordinary, autonomous Roomba). There could even be a Roomba room just for them!