You can now exercise with the help of your MP3 player––without scrolling through the inconsistent grab bag of free yoga and fitness podcasts on iTunes. With iTrain, a new web-based service, you can download workouts from $0.99 to $6.99 each, in every fitness category from yoga to ballet to hip-hop aerobics to cycling. Taught by a stable of Californian personal trainers, fitness teachers, and yogis, the sessions last anywhere from 30 minutes to an hour, and most are set to activity appropriate––yet slightly cheesy––music.

iTrain Cofounders Grace Lazenby and Sebastien Reant dangle the Hollywood bait by having svelte celebs like Sarah Silverman and Courteney Cox endorse the progam. In the latest Entertainment Weekly Silverman says she especially likes iTrain when she’s on the road. It does seem like a good way to squeeze in a workout sans gym or DVD player.

Heath House, a yoga instructor at Yoga Works and Sports Club LA, teaches the company’s iStretch offerings––a 45-minute beginner’s class and a 60-minute advanced version. Lazenby herself guides the iStretch Combination (a fusion of yoga, pilates, and dance). You can buy all of their 11 programs ala carte, or have unlimited access for $50 a year, or $10 a month. For more: iTrain.com