3-O'clock High, that was a great movie. I love how the hero tries every dirty trick he can before 3:00.
The Last Man on Earth. Immensely better than it's Will Smith imitator.
My go-to for hidden gem movies is always Phantom of the Paradise. Where a composer is dragged into the seedy underworld of a record producer's club opening. It's Faust, it's Phantom, it's the 70's. Like a low profile Tommy, prepare for wonderful and crazy at the same time.
Rock and Rule, and Dr Horrible's sing-along blog, both deserves mention as well.