I recently happened across Yoga Today, and it's waaaay cool. Members can stream a different free class every week and download the ones they like for only a few dollars. I like to mix in something new with my standard routines every once in a while to keep myself from getting bored, and Yoga Today is great for that. The classes are pretty long, too, usually about an hour, and often filmed outside in scenic places. My favorite thus far is the Flow class with Adi Amar-- she holds the poses for long enough to really breathe into them, but not for long enough that I have a hard time focusing, and she has the most relaxing voice. If you've been thinking about trying yoga but don't want to commit to a class, or if (like me) your free time is sort of unpredictable, this is a great resource.