I came across this website called YogaDownload.com that I thought looked interesting. Not only do they offer free 20 minute yoga routines for download, but they have lots of options if you are willing to pay a few bucks. Each class can be downloaded in a 20 minute, 30 minute, 60 minute, or sometimes even longer versions. And each class, despite its duration, also comes with a pose guide sheet in PDF format.

I also noticed one option was to build your own custom routine. All the different segments of a good yoga routine are broken into approximately 5 -10 minute sections. You can mix and match, pick and choose, and build your own custom routine. Each segment only costs $.50.  And you also get the pose guides for each segment.