Virtual Piano

http://www.virtualpiano.net/

Takes no actual skill, but I remember playing with this thing a bit ago and trying to find songs on the internet for it. The original Moonlight Sonata I found was this:

 Spoiler

{9e} y i e y i e y i e y i
{8e} y i e y i e y i e y i
{PT} y i P y i {5P} S o P S o
{6e} A o e y i {6e} y u w A u
{9q} e y e y i e y i p e y p
{Yp} u o e u o e u o p u o p
{9p} y i e y i {wG} y o P y o
{8p} t i e t i {8o} t u s u o
{4i} t i e t i e t i e t i
{4O} t i O t i O t i F t i F
{UF} t D O t D O t D F t D F
{YF} A i O A i O y i o y i
{8o} t S w t S {Fq} t y {Oi} t y
{5o} t S w t S {wo} r y w r y
{8t} S o t S o t u o s u o
H i F {qt} i F {Ot} i F {qa} i F
{8s} u o t u o t u o s u o
H i F {qt} i F {Ot} i F {qa} i F
{8s} u o t u o {6s} S D t S D
{Es} y p t y p {5G} y i P y i
{8F} t S O t S {Yo} P u w P u
{9y} w P 9 w P {9y} w t {9y} I e
{5w} P y P y o y o G d o G d
{Ed} p s y p s y p s d p s d
{5d} o G y o G {0H} o G {8H} o G
{Yf} o p u o p u o p {8f} o p
{9g} p d i p d {5f} o G {Rd} i a
{6H} A u p A u G A u o A u
6 A u e A u P A u w A u
6 e y q e y 6 w A 0 w A
{26qy}

They have music charts on the site though which they didn't have before, and it's fun to mess around with for awhile.

Edit: You play by typing the letters, and if they're capitals just hold shift and it changes the note a bit.