Stealthy: Secret Messenger - Chat anonymously with friends & strangers
ASP.NET Identity - ASP.NET Identity is a membership-based software system designed for the authentication and authorization of the users via building an ASP.NET application.
Berkanan - Chat with people nearby. Even offline, on an ✈️.
DotNetOpenAuth - DotNetOpenAuth is a free-to-use compiled library that comes with the real support to your site visitor to login with the help of openIDs via getting control of the ASP.NET control onto the page.
Roomvine - Chatrooms for real life venues, neighborhoods and events
BugMeNot - BugMeNot is a free Internet service that provides usernames and passwords to allow users to bypass the registration process for websites.