Hold it!
I can't believe no one's mentioned the ace attorney games, I've been recently playing Miles Edgeworth: Investigations, and it's reignited my love for the series. Those are awesome games, and everything is done through talking, examining and presenting.
Come to think of it, every point-and-click adventure game ever, except for Full Throttle, the Indy games and maybe some other ones.
It's really surprising only one person has mentioned Monkey Island, and no one's mentioned Loom, Beneath a Steel Sky, Day of the Tentacle, hell even Yahtzee's games are awesome.