Cistron RADIUS server - A free server implementation. Downloads and support are still available, but new development is part of the FreeRADIUS product. - http://www.radius.cistron.nl/
Evolynx RADIUS Server - Windows based application offering authentication via Microsoft SQL server. - http://www.evolynx.com
RadiusReport - Radius log analysis program written in Perl. [GNU GPL, outdated] - http://www.pgregg.com/projects/radiusreport/index.php?cookiesarenotok=1&q=001010171191LxhNPstCSfJopFF1Vpv3bBbwTEZj9nbUUtIKVcnOr6cQLRSHgoLs
XtRadius - Freeware server allowing external processes to determine access (as from a database or other source). FAQ and mailing list information as well as downloads. [Win32] - http://xtradius.sourceforge.net/
Vircom - Makers of VOP Radius server. Site includes key benefits and customer comments. - http://www.vircom.com/
Radical - A free python-based packet analyzer good for evaluating and debugging server installations. Downloads and usage information. - http://www.psychofx.com/radical/
Radiator - Flexible, configurable and extensible server from Open System Consultants. Site includes information about other consulting services and products. - http://www.open.com.au/
OpenRADIUS - Site announces the development and upcoming release of an open, flexible, modular and powerful server and proxy. Site includes a feature list and author's contact information. - http://www.xs4all.nl/~evbergen/e-advies.html
Network Utilities Systems - UK distributor of Steel Belted server. Site includes corporate information, offers and evaluations. - http://www.netutils.com/
The FreeRADIUS Server Project - Open-source successor to Cistron. Site includes release information, and an invitation to new developers. - http://www.freeradius.org/
Cisco Secure Access Control Server - Provides centralized control for networks of access systems. Site includes documentation. - http://www.cisco.com/go/acs
Alepo.com - Providers of full-service authentication, billing and customer management software. - http://www.alepo.com/