DisplayLink has made waves with their USB video chipset technology. It was really a great idea from the start. Add an extra monitor to your PC just by plugging a video adapter into an available USB port. It sounded too good to be true, but over the last few months, they have worked to make a great product that will work well under most uses.
The DL – 120 / 160 engine supports resolutions up to 1680 x 1200 and can even playback DVDs smoothly. If you're one that really needs a lot of space to work with, you can daisy-chain up to 6 monitors together with this technology.
Their most recent breakthrough is support for Aero 3D. The flashy, resource hog that loves to slow down older systems running Vista. It's quite amazing what they have managed to pack into and adapter that simply plugs into a USB port.
DisplayLink Enables Vista's Aero 3D on USB Monitors [via everythingusb]