I think it's hilarious that nearly all of the answers I've read to this one are for schools for people with special abilities. I guess everybody wants to be special. Ah, well, me too...

Xavier's School for Gifted Youngsters
Sky High
Hogwarts School of Witchcraft and Wizardry

Oh,and for those Twilight fans who keep putting "Forks High School" down on their list... HAVE YOU EVER SEEN FORKS? Seriously?! There's a reason they didn't film the movie there, you know.

And I only mean to slightly offend my dear friends that live there. And no offense at all to Pasha, because he's so internationally metropolitan that he's miles above the average Forks resident (which, by the way, if you've ever been to Forks, you'd know is pretty darn fugly and probably not too bright).

Addendum
Oooh! And Star Fleet Academy, and Jedi Academy!