I use the "7-minute workout" android app. There's a bug in it where you can't switch apps in the middle, but I consider this bug to be a feature! For whatever reason, the chromium plugin which was my backup, no longer works (I also liked it because it plays a nice arpeggio at the end, so that's a positively reinforcing primary stimulus).
If you're asking about the workout, I've begun modifying it - I now do the 7 minute workout with 5 lb dumbbells and 5lb ankle weights. I also often do some pull-ups before and after. I also do triangle push ups (or sometimes clap-push ups) instead of the push ups, I do side-to-side push ups (http://www.youtube.com/watch?v=dqQcQrXoYrw) instead of push-up and rotate, and instead of side planks, I do static leg lift, at about 5 degrees elevation.
when I first started out I was doing 7 days a week, but cheating (which is fine, you do whatever to bootstrap) - now I'm doing 5 or 6 days a week, which I think is sufficient.
