In my current "Second Son of a Second Son" campaign, the party has so far been called "The Signers of the Charter of Schiereiland" (see link to story hour in sig)
In my "Out of the Frying Pan" campaign, the group was called dubbed "The Fearless Manticore Killers", but not liking that name they were saddled with, they changed it to "The Keepers of the Gate".
In the past we had a group called "The Oath" and another called "The Sign of Four".