Here's a quicky: We needed to configure someone else's fibre channel switch yesterday, but didn't know its IP address. We did, however, know it was configured in the subnet 192.168.0.x.

So we directly connected our laptop to the FC switch's ethernet port (bypassing the ethernet switch), and configured our own IP as 192.168.0.2 (anything in the same subnet would work). Then we pinged the network broadcast address: ping 192.168.0.255, with this result:

64 bytes from 192.168.0.2: icmp_seq=0 ttl=64 time=0.168 ms
64 bytes from 192.168.0.9: icmp_seq=0 ttl=64 time=0.327 ms (DUP!)

The first response is our own IP, so the second must be the switch! (Press Control-C to stop the once/second repetitions.)

This technique should work on just about any IP device. If you know the subnet, you can find the IP.