Not sure how well the new Matrox TripleHead2Go would work for editing applications but I can imagine that in general it would be great for multitasking any large project. The Matrox TripleHead2Go is a small, palm-sized box that allows you to connect three monitors to your system. It connects to your existing video card and shows up as a 3840×1024 (maximum resolution) widescreen monitor to your system.
Again, it uses the one video card for any video or 3D rendering, but if you have a decently fast system and nice enough video card you will probably find some unique uses for this device. You could even use it with a laptop if you wanted.
The price is $299 plus the cost of those three 30″ Apple LCD screens. Oh, and it’s not compatible with Mac systems.