Great work! You've come up with a fanatic streamlined UI for both entering excercises and doing workouts.

You know you've hit on something great when everyone's reaction is to ask for more features. Here's my wishlist:

* Custom excercise names (so that your autocomplete doesn't have to be comprehensive)

* A timer during the exercises that are timed (I find it annoying while I'm in the gym to constantly set alarms for every exercise in every set and I can't always easily see a clock)

* Ability to add descriptions ("Remember to keep your back straight", settings on machines)

If this is open source, I'd be happy to contribute.