Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.

ScreenTray - A better way to capture, annotate and share screenshots

Shutter - Shutter is a feature-rich screenshot program.

KShare - The free and open source and cross platform screen sharing software

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

Box - Box offers secure content management and collaboration for individuals, teams and businesses, enabling secure file sharing and access to your files online.