Hi there! There are a lot of options out there. I think it really depends on how much you want to pay but there are two that I have used in different price ranges. Mindbody.com and┬áhttp://www.fitsw.com/ are my favorites. Mindbody was very nice and professionally done – the only downside was that it’s pricey. FitSW seems more tailored for individual trainers / smaller gyms because its free – just not quite as polished as Mindbody but still very good.
They both do a great job at creating, recording and sharing workout plans and also diet plans. http://www.fitsw.com/ also is excellent for tracking progress on client fitness. They both are very helpful in helping me manage all my client’s info in one location. Good Luck!
Good timing with this question!
The IDEA Workout Builder was released yesterday and does all the things that you described in your question. You can check it out here www.ideafit.com/exercise-library.
If you want to learn more about the features and start a free trial go here www.ideafit.com/workout-builder
The best I have found (though it is clunky to use) is PTonthenet.com. I love their giant exercise database, and you can add your own custom exercises. I do not like that it takes a long time to reorder the exercises, but it is the best I have found. You can add your own comments and notes to the exercises and program. I read here a while back that IDEA is coming up with their own, am looking forward to trying that one.