Carl Monk has blogged about his experience building and using the MeArm from Phenoptix. The MeArm is a kit made from plastic which, when assembled, gives you a robotic arm controlled using servos. Carl has developed a web interface using the Flash framework to control the arm and has also started to experiment using a PS3 controller. All his code is available here and you can read more about his experience on his blog.
You can buy a MeArm for around £30 from The Pi Hut, 4tronix or Phenoptix including the servos and all the fixings.
You can see Carl’s PS3 controller working with the MeArm in the video embedded below: