If the most disappointing part missed from the film version of Lord of the Rings was Tom Bombadil, the most disappointing omission from the Hobbit was Bilbo's song about the Mirkwood spiders:
Old fat spider spinning in a tree!
Old fat spider can't see me!
Attercop! Attercop!
Won't you stop,
Stop your spinning and look for me!
Old Tomnoddy, all big body,
Old Tomnoddy can't see me!
Attercop! Attercop!
Down you drop!
You'll never catch me up your tree!