http://athletable.com - I built it myself as a side project and, while it's still early days, things are going pretty well so far. The only real bottleneck for me was redoing the entire UI about 30 times. In the end I just told myself that I could always just change it after launch if people didn't like it.
Cheers for the comments. While Athletable is more targeted at companies it would be cool to try and find a way for it to work for schools as well. Can you shoot me an email at nathan [at] nathanhoad [dot] net so we can have a chat.
If you never get around to building the module (I was toying around with the leaderboard/stats app idea for a few years too :-P) then you are always welcome to join Athletable :)
It's certainly not for everyone but it's like the 37signals guys always say: scratch an itch. This has been an itch for a few places I've worked at so I figured I'd make something. Thanks for the feedback though :)
That's a good idea to have the bulk invite. I might show a different form for when the account owner adds the initial players and then the single form for when there are already a few players.
At the moment the ranking algorithm is a blur between ELO and the one used for Tennis. I'd like to eventually give people the option per sport to decide between a few different ranking methods.
The new site has been live for two weeks. We are still working out the rough edges but it's been fun and there are plenty of new things coming out soon!