The Motorola Atrix Lapdock is often used with Raspberry Pi. Here's the Lapdock section of the RasPi Hardware Wiki, which summarizes how the HDMI and USB connections work and has links to many useful Lapdock pages.
Yeah, the Lapdock is cool, but I tried to pick a few things that sparked the imagination. With hundreds and hundreds of projects, it is a bit difficult to pick. There are so many I "wish" I picked, but you just have to go with something. I think the ones chosen were somewhat more imaginative than an inexpensive laptop, which turns out to be something rather easy to create out of a BeagleBone Black using the Lapdock.