I've had a Concept 2 indoor rower for over 15 years. It's been an on and off again part of my fitness program - an excellent full body workout but a hard sell compared to a nice run through the woods. Lately however, as my knees degrade, the low-impact nature of rowing has become more and more attractive.
As partial motivation to get back into it, I upgraded the rather basic speedometer that came with my rower to a new model with more bells and whistles for tracking workouts and progress.
One nice feature of the new monitor is the ability to connect to a PC through a USB cable so that rowing data (e.g. time, distance, pace, frequency of vomiting, etc) can be analyzed. Once on your PC, analysis can provide clear confirmation that your rowing technique and fitness level has plateaued as expected.
A software program called Row Pro takes advantage of this connectivity by providing real-time visuals of your workouts - as you row you see all your numbers as well as a nice animation of a boat on an scenic course. You can even race against a pre-programmed pace boat, a previous workout of your own, or somebody else through the Net.
Row Pro also allows you to upload your rowing workouts to an Concept 2 online logbook so that you can compare your results and distance to others. When I saw this option within Row Pro I expected that I'd be presented with the normal Web 2.0 style prompt of 'Please enter your email & password, we promise not to share with anybody'.
Instead all I had to enter was a 6-digit 'Ranking ID' that I had previously been given by Concept 2. No password necessary for the desktop software to enter rowing workouts to my online log.
I could really screw up a good rower if I were able to guess their Ranking ID as I'd be able to push my workouts into their log. Imagine the shock of some competitive 20-yr old female sculler to discover that she's actually a 43-yr old identity standards architect with poor technique and no stamina.
Clear need for standardized secure & privacy respecting identity web services and a 'rowing workout service interface'.