Richard Grayson* is a classical pianist with a special talent: he improvises classical music around a theme. In these videos, he takes well-known themes from the audience and goes wild.
"The Imperial March" (Darth Vader's Theme) in the Style of Beethoven
Best YouTube comment on this one: "THAT'S NO MOONlight Sonata!"
"Star Wars Theme" in the Style of a Baroque Gavotte
Not quite as awesome as the Imperial March, but quite honestly, this does sound like something you'd hear in a drawing room somewhere.
Annoying Cell Phone Ringtone in the Style of a Renaissance Galliard
Audience member plays ringtone, Grayson makes music.
"Use Ajax, the Foaming Cleanser" as a Tango
For those who remember this tune, this is hilarious.
"It's a Small World" in the Style of Mozart
It's a small, small world.
"Three Blind Mice" in the Style of Scarlatti
See how his fingers run?
"Singin' in the Rain" in the Style of a Chopin Waltz
Apparently this tune is a popular audience request, as Grayson has also done it in the style of Wagner.
* = Note that Richard Grayson is also the name of Robin, of Batman and Robin fame. No relation, I presume.