I played Shadowbane a ton..
We made a guild once called 'My Little Pwnies' It was on the Chaos server. We were all centaurs. It pwned. My character was 'Fip's Little Pwny' I heard that there was a 'Little Pwny' guild in World of Warcraft.. Considering that Shadowbane existed years before WoW and My Little Pwnies existed years before WoW, I'd say we were the first.
Another guild in Shadowbane was 'Order of the Pink Pansies' .. They had pink guild tags and all their board-warrioring sigs were made to be as pansy-like as possible. Great guild..
We made a guild called 'Angry Lawn Gnomes.' We were all dwarf characters and we had a Christmas theme. While everyone else in the game tried to role-play in-game Lore, we roleplayed Christmas. Favorite quote, "You're roleplaying Christmas?! You can't fvcking roleplay Christmas!!" (from an angry enemy guild)
My main guild was Dark Carnival.. ICP-themed guild. Another guild I joined for a while was KGB - Knights of Glory and Beer.