The Gimp is the GNU Image Manipulation Program. The GIMP is an application suitable for such tasks as retouching of photographs, composing and authoring images. Its capabilities as an image manipulation program make it a worthy competitor to other similar programs such as Adobe Photoshop or Corel PhotoPaint. It is available for Linix and Windows.
Inkscape is an Open Source vector graphics editor, with capabilities similar to Illustrator, CorelDraw, or Xara X, using the W3C standard Scalable Vector Graphics (SVG) file format.
XnView is an efficient multimedia viewer, browser and converter.
Fractint is a freeware fractal generator created for IBMPC's and compatible computers.
Project Mayo is creating a new video compression algorithm, OpenDivX, which will allow you to store a feature length video on a CDR.
GIMPguru.org is a resource for those using the GNU Image Manipulation Program (GIMP) to edit photographs. It has a comprehensive suite of image editing tutorials.
PhotoshopContest.com. Here you can take a pre-chosen image, alter it how ever you like and post it for others to view, vote, comment and submit their own versions.