My "desk" is a couple of folding tables, but they work for what I need. My office is also the server room, so I've got a ton of computer equipment whirring away behind me. My "desk" is set up so my monitor isn't visible to anyone else unless the squeeze around behind my desk (which they'd have no need to do). I hate having people looking over my shoulder.
This is also the only room (other than the kitchen) with cabinets and drawers, so I've got plenty of room for all my tools and books and stuff.