I was looking at ways to authenticate users in a web app, but in a way where the main web app doesn’t need to process the password. Something like OpenId, but the authentication server would definitely need to be hosted on an intranet, internet services can’t be accessed by the application server.
My environement is pretty much Java web apps, but it would be interesting to connect the system to other type of apps as well.
You could run your own OpenID server.
You didn’t mention your environment, but another option is to use Windows Authentication with Active Directory if you’re running in a Windows domain situation.