Anyone use a circuit app for iphone?

I do a workout regime of M-W-F Couch to 5K, T-TH Incline walking and am starting daily(hopefully) yoga this week (iPhone has a really neat yoga app that you can design your own yoga workout and it has something like 250 poses to pick from and you just ad them on. Neat!). I got some birthday money, and picked up a couple hand weights (just 5lbs, the 10lbs ones were too expensive) and want to find a circuit training thing I can do with them. I thought about the Shred, as I've done it before, but I only want to do it a few days a week, not every day. I found an app that you can create your own circuit training with different exercises, but I am at a loss for what types of exercises to do. I don't need to it be only weights, as I plan to add some crunches and jumping jacks in there too, but what are some fairly easy hand weight related moves you can think of? The one that immediately comes to mind is squat-thrusts, which I intend to try, but I have an old knee injury that keeps me from doing too many squats.

Any ideas are appreciated. Thanks guys!