The Eyesite LCD arm from office furniture powerhouse Steelcase (available through its Details brand) can hold up to three 24" LCD screens (in both 16:9 and 4:3 aspect ratios) on a single, small-footprint rotating arm.
When you're not using your monitors, the arm can fold flat for even more space on your desktop.
It's cool, but it's not cheap. Depending on exactly how you need it configured, the Eyesite goes for $340 all the way up to $1,100.
For other great solutions for showcasing multiple-montior setups, check out our Roundup of Multiple Monitor Homes.