Greenshot is an open source screen capture tool that is easy to use.

No install required just download, unzip, and execute greenshot.exe. It supports three types of screen captures; region, window, and full screen. Images can be saved as JPEG, GIF, PNG, and BMP. The screen shot can automatically save as a file, sent to a printer, clipboard, or image editor. The image editor supports drawing rectangle, ellipse, line, arrow, and add text. This screen capture tool is easy to use and can allows you to quickly add ellipses, rectangles, lines, and arrows to the image. Be warn this tool on its first execution sets itself up to be automatically when windows is started. This is easy turned off through changing its preferences. It also replaces the windows print screen key for capturing. If you are looking for a screen capture with more capabilities than the windows print key this might be it.