Shutter is a feature-rich screenshot program. You can take a screenshot of a specific area, window, your whole screen, or even of a website - apply different effects to it, draw on it to highlight points, and then upload to an image hosting site, all within one window.
See http://shutter-project.org/about/ for a feature list.
Screen capture program that allows for region/window/full-screen screenshots. Can FTP screenshots and put the URL in your clipboard in a single keystroke. Supports automatic custom naming conventions with variables. Optionally can interface with image editing software.