NodeJS seemed to be an incredibly powerful technology and it is advertised to manage particularly well real-time applications. This is basically what motivated me to try sharing gyro information over the air, using a node.js server as middleman.
The server allows tons user to connect at the same time by giving each one a unique Session ID. Then, from your phone you just have to visit the website as a remote and enter the Session ID.
This project also allowed me to play with polymer which was a fairly new and interesting technology. Other apps uses various other APIs, mainly as an attempt to get familiar using them.
Links:
Technology used: HTML5 Node.js Three.js WebGL Google Maps Api Chart.js Polymer