PDH’s PDF Utils
I wrote a program for Mac OS X (10.5+) that manipulates graphics files. Mostly I use it to convert an .eps to a small .pdf, but the program does some other things. The program comes with no warranty whatsoever. Download PDH’s PDF Utils.
Sage is a computer algebra system that is open-source. I had to zip the Sage worksheet files (sws) in order to upload them to my server, and I recommend using StuffIt Expander to unzip them. There should be a .sws file when unzipped properly.