"BrewPi is an open source fermentation controller that runs on an Arduino (for now) and a Raspberry Pi. It can control your beer temperature with 0.1 degree precision, log temperature data in nice graphs and is fully configurable from a web interface. If you are not into brewing, but do like to thinker with electronics, give the article a read. I had to invent many little things that could be very helpful for other projects too. I can think of a lot of cool things you could that involve controlling an Arduino from a web browser."