ScummVM. ScummVM was originally created to play the SCUMM (Script Creation Utility for Maniac Mansion) games by LucasArts (Maniac Mansion to The Curse of Monkey Island), and many of the people working at Telltale now made those SCUMM games.
So, this post IS relevant in a Six Degrees of Kevin Bacon kind of way. :) Plus, I can't help but promote a previously commercial but now freeware adventure game. :D