Aww, someone beat me to Spamalot's song. But I also love songs that add tidbits of Broadway. Like in Great Big Stuff when Freddy goes, "I can finally afford to see a Broadway show!"
"I haven't got a pail."
"Find your grail, your GRAIL!"
"But it's not missing. It's right on the counter where it's supposed to- defying gravity, my giant cup's gone!"
"Five hundred, twenty-five thousand, six hundred minutes. How do you measure... measure a year?"
"How many times do I have to tell you, it's five hundred twenty-five thousand, five hundred and eighty-five point thirty-two minutes. You will never graduate if you keep basing your math on showtunes."
"You ruin Broadway for me."
"As well I should."