I ended up buying a "desk" from a college kid, made from two file cabinets and a section of countertop. The cabinets give me tons of drawer space, and the top is a nice big, flat surface to work on. It's got a keyboard tray mounted underneath, which frees up even more space on the top. When it's put together, it could almost pass for a real desk (except the countertop's backsplash looks a little funny
). If you didn't want to use countertop, I would think a piece of 1 or 1 1/4" MDF would work just as well. To do an L-shaped desk, you could get some adjustable table legs to support the corner, and join two pieces of MDF to make the L, with a filing cabinet at each end. I'm considering doing something similar with my setup, if I ever have a little more space.
-D.