I've been approaced several times about forming an alliance with another guild, but I could never see how it would be done.
Perhaps a list with some functions to it would help.
Functions like: Lockdown Challenge, Shadow Lair Party Forming, Spontaneous Guild Hall Party, and so on.
It allows you, in essence, to partake in multiple guilds. Having an alliance chat could be useful, or perhaps only guild masters and officers could use the alliance chat as a sort of announcement function. A new tab in the social box wouldn't be bad.
Would allied guilds be able to enter each others' guild halls when private? Could the GM from the allied guild be treated as a member of the other guild (I.e., the guild could give the allied GM an officer position if they wanted)?
I've never been in a guild, so it would be good for various experienced persons to refute and refine my ideas.
I would be up for it as I have some ideas behind it too. But as Reeve said, please do expand on it, if you will.
Decent idea; having some kind of guild relation system would be much appreciated to actually give a purpose to guilds. Try expanding on this idea.