Some developers don't just love code that runs--they also like to get out and run, themselves. And, because they're developers, they love to collect statistics and track their progress over time. If you're one of those people, good news: online service MyFitnessPal has provided the MyFitnessPal API to help its users bring together all their data from various devices and apps in a single place.
Gravatar is an attempt to allow users to have one globally recognized avatar. The service, around for several years, allows a user can set an image as an avatar and have it recognized on a variety of sites. Later, users can change an avatar once and have it change on every Gravatar-enabled site that they use. Though the service is somewhat well known, what is not is its robust API for developers to integrate the Gravatar service into their own sites.