Tank Auth is perhaps the most widely used authentication library for PHP-framework which is built on CodeIgniter. However the author of Tank Auth does not seem to be actively developing to add new features.
For a recent application, I needed something that could offer features like login with third party authentication and this is where i bumped into X Tank Auth.
As the name suggests, X Tank Auth extends the original X Tank Auth to include:
a) Facebook connect
b) Twitter login
c) Google Friend Connect buttons
d) OpenID Google
e) OpenID Yahoo
Who needs more than that ? Amongst these – we can cover more than 90% of the world internet users. The documentation and demo can be found here.