Phil at Dial "M" posted an unbelievable video of Glenn Gould playing a Beethoven bagatelle this week; go there and watch it, and then you can come back here for more miniature fun.
Paul Crossley performing Luciano Berio's "Leaf":
Simon Keenlyside sings "Fin ch'han dal vino" from Don Giovanni (Abbado conducting):
John Zorn and Naked City do "Snagglepuss" live:
And the late, great Dave McKelvy covers Chopin's "Minute Waltz":