Asymptopia Flashcard System uses Motif and LaTeX to produce, manage, and use attractively formatted flashcards. You load some or all of your "collections" and set the timer for pop-up frequency. The GUI interface and "Collection Manager" make creating and modifying flashcards as simple as pushing a single button. A knowledge of LaTeX is only required when entering special symbols.
ImageJ is an image processing program inspired by NIH Image for the Macintosh. It can display, edit, analyze, process, save, and print 8-bit, 16-bit, and 32-bit images. There are modules for biology, astronomy, nuclear medicine, physics, and more. If you can take a picture of something, whether with a microscope, a telescope, an oscilloscope, an xray machine, or a scanner, then this program will let you enhance, manipulate, and measure the results.