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!