I was watching the end credits of “Up” last night (yes, I guess I’m that pathetic that I watch the credits of kid’s movies), but at the very tail end of the credits, there’s a little song played that sounds like a “Spirit of Adventure” novelty jingle that possibly was released when Muntz was in his heyday. So, I thought it would be neat if we all speculated how the jingle fits into the story. When was it released, what kind of business did it do, and how did it affect Muntz? Did he see a profit from its release, and if so, what did he do with his share? Discuss away!
I love the “Spirit of Adventure” song!! (And the version in the film credits is abbreviated/reassembled from the complete version, which is only on the soundtrack download. To clarify, I think you can download it as a separate track, but the point is, the version on the soundtrack album is longer than what they ended up using in the film credits.)
Way way back on another thread, I actually transcribed the full lyrics, with some excellent help and input from miafka. Go about 2/3 of the way down the page linked below and look for the huge gray block. It’s spoiler tagged, but I’m not sure that matters by now.
[url]Up Soundtrack - Up - Pixar Planet Forums
I’ve also wondered about the “history” of the song in the context of the story - since it’s sung in first person, it’s almost implied that Muntz is singing it, but despite all his other accomplishments, that seems a bit of a stretch. 
(Although he’s got enough in the way of money, fame and ego, who knows, maybe he really did record it!)
My guess is that it was a topical novelty song of the day inspired by Muntz and his exploits and “Adventure is out there!” catchphrase, but written and sung by others unconnected to him. It probably hit around 1933 or so, since that’s when Muntz ended up as Life Magazine’s “Man of the Year.” Like a lot of novelty songs, it was probably popular and well-known in its time, but faded into obscurity along with Muntz’s fame. It’s one more way, though, to show what a big celebrity he was in his heyday. I doubt he got any money from it, but he didn’t need the money, and I’m sure he loved having a song about himself.
That’s a good thought, but I think a popular crooner of the 1930’s most likely sang it. I don’t know how familiar you are with the musical Annie, but the singer sounded like the Bert Healy character from that show (or someone similar).
“You’re never fully dressed without a smile!” Oh, yeah, I know “Annie.” (Lots ‘n’ lots of musicals, in fact; I’m a musical fan from way back. 
) You’re right, they did a great job of capturing that '30s sound, with the crooner and the little dance band. I’m ready to see Michael Giacchino write a period musical!