I've created a completely free web app to keep track of players' stats. Since it is a web app, all it needs is a web connection. This supports most browsers and should be able to be used with most smartphones. The only phone that I know it doesn't work on is the Pre's default browser.
Currently, this app will record a player's hands, VPIP, and PFR. It also allows you to save players and keep notes on them.
If you think this is a completely stupid idea, that's fine with me. I'm not trying to make any money off of this. It was done in my spare time for fun and to learn.
If there is enough demand, I will continue to make this better. Thoughts for the future include themes (the current design needs an update), color coding, offline support, and perhaps bankroll tracking, along with general speed and bug fixes.
Let me know if you find any bugs- please include your phone and browser information.