Over the last several weeks, I've been working on a pretty nice little app that will allow for the integration of several social networking sites with Sitecore user profiles. As a part of this application, I've been utilizing the Sitecore 6.0 API to manage the creation and manipulation of custom user profile properties (for storing usernames, passwords, etc.).
I've summarized my experience at LearnSitecore, so be sure to head on over and check out my latest article.