Instead of paying for a commercial sprinkler timer control computer, Arduino enthusiast "nicoo" devised his own system based on an Arduino with Ethernet connection, connected relays to control solenoid valves and related circuitry. The next result is a system that waters the garden on a timer - except when rain is forecast (weather information is scraped from a website), can be controlled over the web, and tweets the results of the watering when it's finished. Now that's automation...
Although it may sound complex, when broken down into smaller parts it is quite simple. So to get started, check out the instructions page here. And we're on twitter, so follow us for news and product updates as well.
Moving forward you can use less parts than the original with some new products from Freetronics. The system base could be handled with Freetronics EtherTen. Apart from being fully Arduino Uno-compatible, it has onboard Ethernet, microSD socket and supports optional Power-over-Ethernet:
