A few months back I was setting up two three-lcd monitor arms. I had an extra "arm" left over, so I decided to try and build a laptop stand that would hover over my desk.
I used aluminum angle beams and hollow tubes with threaded rods and was able to build something that works. The only tools I needed were a standard drill and a hacksaw. I used 3/8" x 1/8" adhesive rubber weatherstripping to provide a no-slip surface that also protects the bottom of the laptop from being scratches by the bars. It keeps my laptop monitor in line with my other monitors, and clears up all the desk space under it.
If I recall correctly, I spent about $30 on parts - I bought some aluminum I didn't need. It took a couple hours to design and put together.
Here are some pictures:
on February 5, 2010