Aaron put a comment in my last post with a link to this site - http://www.turbotraining.co.uk/. Its bascially an online turbo workout application. You choose a plan based on what you want to do and the equipment you have, click the start button and away you go. The timer starts and the zone you are in is highlighted for its duration. Its a really nice idea, as my tt programs are printouts which get crumpled up, covered in sweat etc.
There are a few programs up there now, but once you register you can upload your own programs, and rate other peoples programs.