glSwarm is, in essence, a set of c++ classes. There is not really a "program" to download. Instead, one should download the source code. At any given time, the code may or may not build as-is, depending on recent development activities. If you are interested in getting it to build but are having trouble, please email Dan.
The best way to get started is to download the source from CVS:cvs -d:pserver:email@example.com:/cvsroot/glswarm login
cvs -z3 -d:pserver:firstname.lastname@example.org:/cvsroot/glswarm co glswarm
The makefile in the CVS is out of date, so simply typing make or make glutswarm may not work. Following any standard directions for getting a GLUT program to compile on your system should work.