Depends on if you want functional or pretty. I choose the former. I went out and bought a hollow core door from Lowes and 2 metal filing cabinets. Walla! A long, flat desk that can fit multiple monitors/printer/etc. Yeah, you get some giggles from people saying how ghetto it is, but then they realize they spent 3 or 4 times as much and still dont have any desk space.
If you don't like the door meathod, go buy one of those countertops. You could get one of those faux marble or something and would be real easy to clean.