I recently started using CGI::Builder having previously used CGI::Application. CGI::Builder provides an excellent integration with session, template and user authentication modules. It has extremely thorough documentation and the examples are clear and understandable. The mailing-list has been extremely helpful with all queries.
CGI::Builder::Auth is a good addition to the CGI::Builder Framework. It provides simple User Verification and Administration. The documentation is comprehensive and the examples cover all aspects of the Module.