I like to have a little album of cool moments from MMOs and single player games. Picasa then draws from the screencap folder for my screen saver, which is pretty cute. Better than flying toaster or whatever, at any rate. I don't usually bother with hiding my UI, and I tend to let FRAPS take the screencaps every third second until I turn it off. Then I occasionally drill into that folder and get rid of the less interesting stuff and keep the funny or cool ones.