As part of the NSF-supported Education Infrastructure project, Drs. Shaffer and Heath have supervised students to develops a tool called Swan to help with visualization of algorithms and related data structures.
Please see the online WWW files. There you can download appropriate files and build them for various operating systems: Solaris, Ultrix, OSF.
For this course, the most relevant algorithm animation is about Huffman coding, one of the most common lossless compression methods, that is a key part of JPEG, MPEG, etc.
The character/frequency pairs are initially read from stdin, and there are two sample files (sample.input and letters.freq) that show the syntax.
After that you either STEP or RUN through the construction of the tree. Then you can do encoding and decoding from the Swan window's input/ouput line.
Thanks go to Jeff Nielsen who developed many animations using Swan this semester, and who can be reached at jnielsen@csgrad.cs.vt.edu