The Ipsilon project implements an Identity Provider that is easy to use and configure. And it aims at providing installation scripts for applications that can use an Apache fronted to perform user authentication.
An IdP server allows users to authenticate against any identity provider whether that is a corporate LDAP server or even just local files or custom pluggable modules and allows applications to authenticate users while being completely agnostic of what authentication infrastructure is being used.
Applications can currently use the SAML2 or OpenID protocol to talk to the Ipsilon identity provider.