Tamrahan
Cathlete
This link came up from a member on mfp I'm not sure if it has come up on this forum or not but I haven't seen it so I thought I'd post a link. It's a bit different than cardio coaches and it is free, you just download it to your iPod. It follows the coolrunning.com c25k plan-warmup, run/walk intervals, cooldown. He keeps track of the timing so you just do what he says Eg: "slow down to a brisk walk for x minutes, I'll let you know when it's time to run again" He doesn't talk much and the music is pretty good. These are aproximatly 30 minutes in lenth.
http://www.ullreys.com/robert/Podcasts/page6/page6.html
http://www.ullreys.com/robert/Podcasts/page6/page6.html