A feature of Neutron that is probably less known, is that most network resources have a description field available in their APIs. This is pretty useful to pass some readable information about what a resource is for. This exists for everything from routers and networks to security group rules.
I noticed that for Floating IP addresses, this field was not exposed in the OpenStack dashboard - so I wrote a small patch. It is probably the OpenStack-patch that have gone through with the least effort.
Description field for Floating IP addresses. Coming to Horizon in Queens.