Shutter is a feature-rich screenshot program. You can take a screenshot of a specific area, window, your whole screen, or even a Web site, apply different effects to it, draw on it to highlight points, and then upload to an image hosting site, all within one window.
Install shutter in ubuntu 10.10/10/04/9.10
Open the terminal and run the following commands
sudo add-apt-repository ppa:shutter/ppa
sudo apt-get update
sudo apt-get install shutter