No one mentioned my favorites for a good MP3 ride.
www.itrain.com - their iCycles are the most like a real spin class. I like Keith's voice, too. I have also adapter the iClimbs to the bike. They do have some rap music which I'm not fond of, but that's okay.
Cardio Coach -www.cardiocoach.com - Coach Sean O'Malley offers varying length interval training. They are really designed for any equipment (bike, treadmill, elliptical...), but I love them on my trainer. They do tend to be rather "inspirational" (not religious - but he says things like "You have a choice in your actions - you can choose actions that will lead you six feet under, or 6000 feet into the sky.") But, he also has the knack to put encouragement right when you need it. I enjoy him.
Christine
Life is not measured by the number of breaths we take, but by the moments that take our breath away.
Cycle! It's Good for the Wattle; it's good for the can!