Thum.io - A real-time website screenshot generator
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Microlink screenshot - Take a screenshot of any website
Shutter - Shutter is a feature-rich screenshot program.
Screenshot Tracker - Capture and keep track of full-sized web page screenshots
Snipping Tool - Use Snipping Tool to capture a screen shot, or snip, of any object on your screen, and then annotate, save, or share the image