Well, Radiator is such a product. To quote directly from their website (http://www.open.com.au/radiator/index.html):

Radiator is the highly flexible, configurable and extensible Radius server from Open System Consultants. Designed from the ground up to offer features and options not found in any other Radius server, it uses the latest Object Oriented technology to achieve superior reliability and flexibility.

With more than 20 different authentication methods available, and support for most Unix and PC platforms, Radiator is the Radius server for serious ISPs and carriers who want power and flexibility to meet the needs of their growing user base.

There is quite a good article about it on www.perl.com: http://www.perl.com/pub/a/2002/10/15/radiator.html.

Additionally, Rational is maintaining an interface to Rational Clearcase (see http://search.cpan.org/author/RATL/).