Jogcast is a very rough-and-ready Perl script which takes a simple list of run, walk, jog, etc. times and inserts voice commands to that effect in one or more MP3 files. The idea is to let you time your workout according to a plan, without constantly checking your watch. Inspired by the Couch-to-5K Running Plan.
This was written by, and for, a programmer, so it's not the most user-friendly thing that ever existed. Usage is fairly straightforward, though, and it does its one job well.
Please view the README file for requirements and usage instructions.