How do sites like SO allow you to authenticate yourself via Facebook, OpenID, Google, Blogger, Twitter, etc?
I'm writing an ASP.NET (C#) site, and I'd like to be able to accept logins like this, in addition to offering the regular plain vanilla username/password that any other site has.
Where do I start?
You might want to try DotNetOpenAuth
Here's a similar question on SO with some more links
I would suggest you look at http://www.dotnetopenauth.net/
I believe SO may actually use this library - they definitely donated to the project this year (see http://blog.stackoverflow.com/2010/12/stack-overflow-gives-back-2010/).
