My team at a recent Startup Weekend did this. RasPI with a PID loop turning a fan on (increase heat)/off (decrease heat). The RasPI fed this into a backend ser

My team at a recent Startup Weekend did this. RasPI with a PID loop turning a fan on (increase heat)/off (decrease heat). The RasPI fed this into a backend server via websocket. We through a front end on to graph the temp, humidity etc. We could even set the temp and turn the fans on/off via the site.