GIMP is a very powerful image manipulation program. It has many similarities with older versions of Photoshop. GIMP is overkill for typical cropping tasks, but is an excellent tool to have.

Inkscape is a free vector graphics program. It sports an intuitive interface and is SVG standard compliant.

Camstudio is a great screen recorder. Whether you need to record a video of a computer problem you're having, or make a tutorial to help someone else with a computer task, Camstudio is an excellent option.

VirtualDub is a powerful video editing tool. It's fairly complex, and definitely not the most intuitive program I've used. But if you want a powerful, free video editing tool, VirtualDub is worth getting to know.