You've no doubt heard of Arduino by now, but there's no great shame if you don't know much more beyond that. And if you're curious, Bob from I Like to Make Stuff has a great, quick, just-the-basics ...

This tutorial will guide you through the process of building a tachometer around an Arduino. Tachometers are used to measure rotation rate in Revolutions Per Minute ...

You can easily add Internet-based control for your Arduino if it is close enough to your server to be connected via USB. This tutorial will give the basics you need to get it working. The gist of this ...