I know you said to avoid iPhone specific apps, but being a new user of the iPhone I can't help but blurb a little about it here. I also have some non-iPhone specific ideas below.
This post is less of a "what's available" and more of a "I wish..." angle. Buyer beware.
So being a previous Sidekick, 2-time Treo user and a current owner of an HTC Mogul (as well as my brand new iPhone 3G) I feel qualified enough to state that the iPhone is literally about 3 years ahead of the competition. The possibility for apps on this platform are endless, and Apple's innovation is only going pave the way for every other phone manufacturer to copy their features. So looking to them to provide never-before-seen mobile applications is important. Hell, the iPhone apps for Gmail, Facebook and Myspace are the best mobile apps I have ever seen, and we won't even talk about the really good ones. But I digress. My iPhone idea would be to write a walking application that uses the internal iPhone accelerometers to track number of footsteps taken. Combine that with the GPS features and you now have a complex way of measuring how many footsteps have taken place in a given time, or a given day, and is correlated to how much distance was traveled. Plug that into an interactive website or social networking site (Facebook app?) and let people share real time stats, walking routes / trails, compete for steps per minute, etc. How's that for a mobile workout app? Only the iPhone can do this today.
Other ideas for non-iPhones. How about a bluetooth heart rate monitor that will work with any phone?
How about a bluetooth earset that also records steps taken? We wear those stupid things on our ears all day, might as well get some benefit out of them while we're all looking like complete nerds.
How about a mobile app that ties into a workout web app? Part of the problem with workouts is recording your workout, ie, how many reps/sets you did, on which machine with which weight. If you transcribe that into a journal, and then transcribe that onto a website, that's just too much work for some people. If you had a mobile app that you put all that info directly into, which talked directly to a workout social networking website, you'd be golden. Then the next day, your workout plan would be ready for you on your phone and you're good to go. Just like having push calendaring keeps us on time for our appointments, push workout plans could help us stay on our workout plans.
Take that same idea and apply it to meal plans and schedules. Add a database of foods and calories for people on the run who want to find out how much fat is in a Whopper. Plug those meal records into social networking. Think Facebook apps here.
How about a mobile app so people who go to the same gyms can find workout buddies? How about a beacon app to broadcast to other gym rats your workout routine and see if they want to join in or chat about it?
A beacon app could tell you how many people are at the gym, saving you a wasted trip if it's too busy.
I could go on and on, but those ideas are probably the most easily implementable in the next 3-5 years. I've been dying for a health-oriented social networking site for ages.
Perhaps the mobile market is the best way to break new ground?
Ok, back to worshipping my iPhone.