Master Spark is one of the few songs I can consistently remember the tune to and sing (Yes, sing <.< It's basically humming, just with gibberish words that sound vaguely Japanese but I'm relatively sure aren't...) and then I'll off and on remember the tune from other Touhou songs as well. Maid and the Pocket Watch of Blood, Riverside View, Doll Judgement, Casket of Star...