I recently picked up a Motorola LapDock from eBay. It was originally used as a keyboard, trackpad, and screen in a laptop format for the Atrix smartphone, but w

I recently picked up a Motorola LapDock from eBay. It was originally used as a keyboard, trackpad, and screen in a laptop format for the Atrix smartphone, but with some converter cables, you can plug into any machine with HDMI and USB and use it exactly as you describe. It's finicky, but works well enough to be useful. Total cost for the LapDock and cables was under $100.