First off, I must introduce all of you to Thurl Ravenscroft, the patron saint of She'll Grow Back. That's him, right there to the right. He's the original voice of Tony The Tiger, and the singer of "You're A Mean One, Mr. Grinch" (not Boris Karloff, as so many people assume). During his 70-year career, he also did quite a bit of work with Disney. He voiced characters for The Enchanted Tiki Room, Pirates of the Caribbean, narrated The Disneyland Railroad, and sang lead on this song, "Grim Grinning Ghosts".
This song is, of course, the theme song (and for the most part the entire musical experience) of The Haunted Mansion. While riding, you hear many different versions of the song, most of which you can hear separately by clicking through to DoomBuggies.com, a model fansite.
Version 1 below is the original recording from the ride. Version 2 is a slower rerecording Thurl did for a 1996 singalong video. Version 3 does not, sadly, feature Thurl. It's a faux-classical version recorded for play in Disneyland's extremely exclusive Club 33. Version 4 is a surf instrumental of the song. Version 5 is a ragtime version, from one of Disney's ragtime Main Street pianists. (There's a nice swing cover excerpted here.) Version 6 is a live recording by Buckethead (sometime guitarist from Guns N Roses), as he plays with pitch control on his vocal mike. Finally, we have a ridiculously good cover by Barenaked Ladies. (If you'd like to hear yet more versions, make sure to click through to Doombuggies.com up above, and go to the next page.)