ExtraInfo documents are also one possibility for communicatingOutboundBindAddress values, as well.
While publising OBA's may be wanted by censoring firewall pedants, it's not productive for relay operators who wish, as is their right, to offer tor users the chance to use exit IP's that are *not* listed in the consensus for easy scraping by such pedants, such that users might have more of a chance to participate freely reading materials on the internet, communicating on forums etc, where such pedants have otherwise blocked access.
Operators that OBA, NAT, VPN, or provide VPN termination IP's on their nodes, have my support as they offering additional censorship resistant services of that kind, even if only marginal due to exit testing, it's still benefit against lazy censors.
Other than that, many times suggested has been ways for relays and primarily third parties subscribable services to calculate, denote, and promulgate for user consumption various "extra" properties of relays, such as Web of Trust (WoT), diversity, other metrics. If not in "Contact", a second, community defined and wikified field could be adopted. Or made purely third party lookup subscription or patch if all such other is refused in tor directly.
Thanks Nusenu, and for all your various work.