Irfanview, a free and powerful image viewer for Windows. Use xv on Unix. There are several image viewers for the Mac, but I haven't tried them. Please let me know if you can recommend a favorite.
ImageJ, an image processing program written in Java, callable from Matlab, and extensible with plugins. This program, developed at the National Institutes of Health, includes a very large collection of user-contributed image processing plugins.
Data Sets and Tools
There are too many images and video sequences available for download to list here. Just use Google to find them. You can also use your own cell phone or PDA.
