Relating to working with four monitors I didn't share my monitors that I use at work in my first post, so here they are:
2x 19" HP monitors at 1440x900
1x Hanns-G 22" at 1920x1080
1x Gateway 22" at 1920x1080
I typically have one of the larger ones being used for research/looking things up on the Internet while the other larger monitor is used for writing code. The two smaller monitors change depending on what I'm working on. Sometimes one may have a working copy of the app running, the other monitor may have a database GUI open, or SSH connections, or FTP running to work with various things.
I am able to orient myself so that I can see two or three monitors at any given time. Having each monitor for something specific allows me to easily switch between them like a lot of people switch between windows, I just don't have to deal with as much of that minimizing, maximizing, and adjusting of Windows.
At home on a Mac I use something called Mission Control which I find very interesting. I mapped one of the mouse buttons that usually will go back/forward in a web browser so that it will launch Mission Control. Once I'm in Mission Control I can switch between different desktops, each having different windows open. I can then have several monitors like I did before, but I can also have different desktops for different things. If I'm working on multiple projects at any given time I can create a desktop for each project. I find Mission Control incredibly useful. Gnome has something very similar to Mission Control that I use when I'm using my Linux laptop.