I have used link-local addresses to connect to routerboards without having to use a serial console while configuring them.
(This is helpful for things that can't be done with a console, such as routing filters with multiple types of routes to match. Everything, even exports, say you can do protocol=connect,static, but you will get an error if you try that on the console.)
I would discover the link local address by pinging like this:
ping ff02::1 -I <nameofinterface>
And then look at the address that responds that is NOT my computer. Then I could connect with something like [fe80::2eec:3adf:e95f:a44%interfacename]
This worked great, but in recent versions, I get no ICMP replies when pinging the multicast address ff02::1. Is this a bug? A "feature"? Something I can fix with configuration? (but that kind of defeats how I use this).