One way I would kill time on The Legend of Zelda: Ocarina of Time was trying to figure out how to play other songs on the in-game ocarina. On one occassion, I managed to pick out the Pokemon Red/Blue opening after hearing the original only once. Aside from a few botched notes, it was pretty much an exact interpretation of the original.
Maybe when I dust off my N64 again, I’ll see if I remember it still.
Happy gaming,
SparklingBlue