On their website, UK industrial design firm Tinker. it! promotes the arduino, a credit-card-sized circuit board laden with sockets and sold by Tinker Tools. What does this little thing do? Well, that depends on you, really--the arduino is aimed at the physical hacker/tinkerer set.
[The arduino] comes with a series of sockets into which tinkerers can plug light or motion sensors and a similar set for plugging whatever gadget they want to control into. Using a laptop, the arduino can be told what to do when a particular event happens - for example, when a motion sensor is triggered, it powers up a motor.
Look at any recent electronic art installation and the chances are that behind the scenes there's an arduino. In fact, [Tinker. it! co-founder Alexandra] Deschamps-Sonsino believes more than 100,000 arduino boards have now been sold around the world, although it is difficult to give an exact figure - in keeping with the open ethos of the movement, plans are available that allow people to make their own.