CamStudio is able to record all screen and audio activity on your computer and create industry-standard AVI video files. (GPL)

Greenshot is a revolutionary screenshot tool optimized for productivity. (GPL)

recordMyDesktop is a desktop session recorder for GNU/linux that attemps to be easy to use, yet also effective at it's primary task. (GPL)

Shutter is a feature-rich screenshot program. You can take a screenshot of a specific area, window, your whole screen, apply different effects to it, and then upload to an image hosting site, all within one window. (GPL)

ZScreen is an open-source screen capture program that allows for region/window/full-screen screenshots. (GPL)