@HostName(servername) would return the HTTP hostname for the given Domino servername e.g. @HostName("Server1/Mega") might return "megadom01.megacorp.com".
Ah, view column formulae are always the problem. I'd certainly like to see some feature that would enable simple post processing of views. Hang on, I feel an idea coming on ...
Multiple site docs ... hmm ... how about a precedence indicator on the site documents, so that admins could control how Domino resolves ambiguous references?