"I have two multi-monitor setups. The first is my desktop which has only 4 monitors because I can't find space for 5. The big two monitors are powered by a dual headed card. The small CRT is for video preview only from my video deck, and the little monitor on top is driven by an EVGA UV Plus+ DVI-USB adapter.
All these monitors are incredibly useful especially in video editing. Video plays on the CRT, and I put all the editing controls, media database, etc on the right-most monitor. That frees up the entire center monitor for the video timeline. The fourth monitor was great as I put all my editing notes on it (you can see them in the picture).
For photoshop: it's very similar. All toolbars, pallets, and docks are on the left monitor, leaving the center monitor free for only my photo. (I'll rotate that monitor if I'm working on a portrait shot instead of a landscape). On my little EVGA monitor, I'll put notes, Adobe Bridge, or a tutorial if I'm trying something new. I've gotten so attached to this setup that I can't work on Photoshop with one monitor anymore.
The second setup is for my laptop. I've got an ASUS VW223B monitor with built-in DisplayLink support. Into the monitor's built-in hub, I plug USB sound, and mouse. This gives me essentially a docking station that fires everything up with a single USB cable - very tidy.
The ASUS monitor doesn't normally go vertical, but I love using vertical monitors for writing or surfing, so I use a Neoflex stand attached to the VESA bracket on the ASUS. This stand is much better as it allows me to rotate the monitor and has a height adjustment. At about $210 for both, it gives me more functionality than monitors $100 more. As you can see in the picture, there's space for at least one more..."
Thanks Rob for showing us your desktop, er, desktops!