Not sure whether folks have heard of it or not, but Podrunner is a free (FREE!) mix of music to run and/or workout to. Mostly techno-ish type stuff and I thought I would hate it, but after about 5 minutes I was totally in the groove and not worrying whether the next song on my ipod would suck. They also appear to have mixes/programs for the couch to 5K program as well as 8 and 10K programs. Check them out here:
DJ Steve Boyett - Mixes