Libravatar is a service which delivers your avatar (profile picture) to other websites. If you create an account with us, your photo could start popping up next to forum posts or blog comments on any site where you left your email address.
This service is powered by Free and Open Source software called ivatar. With this software you can also run your own instance and serve avatars yourself.
Can also generate pixel art avatars of several varieties.
Source code: https://git.linux-kernel.at/oliver/ivatar/