Arduinos are awesome. I've never done anything terribly code intensive, but a few months ago I built a water-sensor network for the wells around my parents' house. The sensors keep track of the water level in each of the wells, and sound an alarm when the water level rises above a certain point.

I did this with about a year of programming experience, and zero experience with hardware, and all for about $80. It helps that the Arduino language has a great IDE that takes care of compiling and uploading the code to the board.

http://www.arduino.cc is the main Arduino site. It has the IDE, documentation, examples, and links to websites that sell boards and accessories. Boards run about $35. Cheap and effective.