Multimedia software

Image editing software - free open source

Web Resizer - Crop, resize and recolor images, including setting compress quality with this online tool.
Picnik - Crop, resize, color correct and more. This is an online tool.
Fotoflexer - Besides the basics, it includes layers, animation and effects. Also has a morph tool. Try it!This is an online tool.
Photoscape - Photo editor with lots of features, also includes animated gif creator, combines multiple photos in one file, and converts RAW to JPG.
Win, Mac, Linux
Paint.net - Has layers, blend modes, selection tools, special effects, and much more; take a look.
Win
GIMP - If you like Photoshop, give GIMP a try. Go to the download page for your computer OS and read the instructions carefully. Win, Mac, UNIX-Linux

Avidemux - This video editor supports many file types, including AVI, DVD compatible MPEG files, MP4 and ASF; it uses a variety of codecs.
http://avidemux.sourceforge.net/
Win - Mac - Linux
Wax - Use for video compositing and some interesting special effects. Outputs to AVI, MPEG, WAV, Flash, all popular image formats. Win

Vector Magic - converters bitmap images into vector images (autotrace) http://vectormagic.stanford.edu
Super converts a wide range of video and audio file formats to the new format.
AVI, WMV, ASF, Realvideo, Quicktime, and more, including .3gp used on some mobile phones
Overview of Super