Seeing the effects of guild affiliation

See, this post by superdeluxe over on Livejournal, I think, constitutes exactly the kind of great "emergent gameplay" that the folks at Terra Nova are so ga-ga over lately. The poster found his way into a guild that, because of their size, is well-known and loved on his side of the server, and as a result, he finds that he's getting "10-20 times the amount of Free buffs/free stuff/bow's/hugs etc than I did before."

He's not on an RP server-- rather, his guild has just built up a social reputation, and he's benefiting from it. Likewise, a commenter on the post says his guild, because of PvP, has a negative reputation, and as a result, he became Kill-on-Sight for a number of opposing faction guilds around the server. The only way this stuff is built into the game is that Blizzard has put everyone's guild name above their character, and players have socially created all the rest of these affiliations themselves.

Now, a lot of it simply follows from common sense: my guild isn't huge, but every time I see someone with my guild name, I'll /wave and buff, even if it's someone I don't know that well. We haven't really made too many enemies (well, we did have a little tussle with the alliance that we seperated from, but they've since dissolved), but as we've moved further and further into the endgame (we're still not server-first, but we're working on it), we've created more and more of a reputation as a known and trusted guild on the server.

What other examples of this have you seen? I'm fascinated with the way players treat each other based on guild affiliation-- at their essence, guilds are mostly the social structure within a realm in the World of Warcraft.