[alecdbrooks]

It looks like Jawbone has a reasonable-looking API [1]. Alternatively, you can set up Beeminder [2] to collect the data (or for Fitbit) for free and then use Beeminder's API [3].

[1]: https://jawbone.com/up/developer [2]: https://www.beeminder.com [2]: https://www.beeminder.com/api