I figured more or less the same, aside from the odd time when I program, but I use my second screen for stuff like having msn open without needing to minimize things to check the online list, (and having the conversations over the main window, instead of taking over my main monitor) and other things. I keep winamp over the left side of my second monitor, over top of things so I can see what's playing without needing to interrupt myself and move things around. Any time I have a full screen app, I can keep winamp visible in the second monitor, which saves me from needing to alt+tab out to check what's playing. Any time I have something like Fruityloops, Adobe Audition, or any other program that can use the full screen and detach child windows, I'll use a child window on the other screen, (like the playlist part of Fruityloops). It increases productivity, and is generally helpful.
It's not just that, but the fact that you get used to having it there, and using it in certain situations, so that when you don't have it there, it feels weird.
I never thought I'd get so addicted to having a second screen myself, but nevertheless, I am.