Have you heard of ChallengeLoop? http://www.challengeloop.com. ChallengeLoop allows you to motivate your clients to achieve their fitness goals and track their progress along the way. It is both an iPhone app and website.
Try the ‘3 in 1 Timer’. It has an interval timer, stopwatch and countdown timer. You can save presets for when you run your sessions.
It’s pretty easy to use. I use it to run group classes, and train individuals. Big buttons for my giant fingers. ha. No complaints.
Try the training notebook ( thetrainingnotebook.com ) I’ve been using it for over a year and it’s been great! it’s not perfect it could be a little faster and more program lines but it’s the best one out there so far. I use it on my iPad Air and it’s been great no mo paper work for me it’s all on my iPad