Ask HN: Compelling uses for RADIUS?

I am now de facto the 'network' guy _and_ the linux guy, for an organization providing SaaS (eDiscovery). Go, me.

Reading up on the switches and firewall I'm installing I see that if I have a RADIUS server I can

- Authenticate users to the switch, and router.

- Control access to VLAN.

This is all kinds of cool, and will probably cause me to install a RADIUS server, because 1 is handy and 2 strikes me as a great way to assert control over my network.

Are there any other compelling uses for a RADIUS server?