I heard about Arduino before, however I never took the time to look into it. In case you don't know, Arduino is an open source electronic board that allows you to easily interact with it and create... just about anything!
If it wasn't clear up until now, I am a great enthusiast of open source software and hardware, and Arduino seems to be both. It has a very community of contributes and many people customize it for their own needs.
What I like most about it that you can find free sketches for things you might want to do. Things like a server, barometer, and even a well designed mirror that plays music from your iPod. All available freely.
More than that, with organizations like Open Hardware and the dropping prices of 3D printers we are looking into a new age of making. One that even allows you to build your own village! (bulldozers and everything)
If you are interested in that sort of stuff check out he video below, it is a TED about Arduino and shows off some neat stuff people do.
BTW, I know of there is concern that things like Arduino are "dumbing" down electronics. People use it and don't understand all the implications of what they are doing. In software we had the same debate regarding .Net, which makes programming so simple we sometimes feel like .Net developers are cheating and are not real developers. And I am also reminded of the debate that Ubuntu is not real Linux because it is so simple.
I am against such approaches. While I myself like to understand exactly what and why everything occurs (i.e. low-level programming), I know most people don't, and these things (Arduino, Ubuntu, not so sure about .Net) are good things. Things may be simpler, but more people use them and that is the important thing.