Built something like this at YC Hacks, except any device or even a webpage could function as the server and provide a real-time or REST interface. We had 5 dem

Built something like this at YC Hacks, except any device or even a webpage could function as the server and provide a real-time or REST interface. We had 5 demo apps showing off various examples, including a super cool two-factor auth demo.. Trying to explain the concept to people in 30 seconds was non-trivial.