http://www-static.cc.gatech.edu/gvu/softviz/algoanim/xtango.html

From the XTANGO website:

"XTANGO is a general purpose algorithm animation system that supports programmers developing color, real-time, 2 & 1/2 dimensional, smooth animations of their own algorithms and programs. The focus of the system is on ease-of-use. XTANGO utilizes the path-transition animation paradigm which helps move animation design to an abstract, high level. Programmers need not be graphics experts to develop their own animations."

TANGO/XTANGO was well known in its time, and the distribution documentation says it includes over 50 animations. However, this system appears to have been replaced by Polka/SAMBA. Potential users will need to download and compile the software for an X-Windows system.