Haggis McMutton is voiced by none other than Alan Young (Scrooge McDuck, himself)
You'll find it hard not to think of Cutthroat Bill when hearing Jecht's voice in Final Fantasy X.
Also, Gary freaking Coleman as Kenny Falmouth, along with Mary Kay Bergman as Minnie "Stronie" Goodsoup, Glenn Quinn (of Angel fame) as Pirate #5, Terry McGovern ("Launchpad McQuack") as Captain Blondebeard and Cruff, and Earl Boen (of Terminator fame) as LeChuck.
Promoted Fanboy: Dominic Armato, Monkey Island Fanboy and voice of Guybrush Threepwood.
Talking to Himself: There are a lot of actors who voiced multiple characters (even though said characters have never met each other). They are: Alexandra Boyd, who does Elaine and the Son Pirate; Denny Delk, who does Murray, Skully and the Father Pirate; Michael Sorich, who does Edward Van Helgen and Charles DeGoulash the Ghost Groom; the aforementioned Terry McGovern; Tom Kane as Captain René Rottingham and the Lost (Flying) Welshman; Harvey Jason as the Cabaña Boy and Effete LaFoot; S. Scott Bullock as Lemonhead and Pirate #2; Victor Raider-Wexler as Slappy Cromwell and the Snowcone Guy; Dave Fennoy as King André and Pirate #3; George DelHoyo as Palido Domingo and Pirate #1; and Roger Behr as Mort the Gravedigger, Stu Boyle and Pirate #4.