I have created a Linkedin authorization plugin for Moodle. This enables you to login to a Moodlesite using your LinkedIn username and password. After logging in your firstname, lastname, current posistion, country, city and profile picture are shown in Moodle. This plugin mainly targets companies that use Moodle for eduction.
The plugin is available for Moodle 2 and newer, you can find it in the Moodle Plugin Database.