According to Wikipedia:
Frédéric Chopin's Fantaisie-Impromptu in C-sharp minor, Op. posth. 66, is a solo piano composition and one of his best-known pieces. It was composed in 1834 and dedicated to Julian Fontana, who published the piece in spite of Chopin's request not to do so.
Some aspects of this piece are similar to Beethoven's Moonlight Sonata, which is also in C-sharp minor. Two measures after the melody begins, an abrupt run up and down has exactly the same notes as the cadenza in movement 3 (Presto agitato) of that work. The climax on a six-four chord is similar in both pieces.[1] Also, Fantaisie-Impromptu's middle part is in D-flat major, whereas, the second movement of the Moonlight Sonata is in D-flat major. The first and third movements are in C-sharp minor. READ MORE HERE.
Here's one of the best versions available in the net - played by Li Yundi, a Chinese classical pianist. Born in Chongqing, Li is most well known for being the youngest pianist to win the International Frédéric Chopin Piano Competition at the age of eighteen years in the year 2000. He now resides in Hong Kong.
CLICK HERE FOR THE FANTASTIC VIDEO CLIP of Li Yundi playing Fantasie Impromptu! Mind you, not only is he talented, he is also VERY cute :-).
Tonight, I have listened to it for more than ten times already!!! he truly plays it sooooooooooooooooooo beautifully and brings out the romantic and dynamic nuances of the piece in such an exqusitely elegant manner!!!
Enjoy....
walla Oh dear. You've got my attention.
His Nocturnes in E Flat Major and C Sharp Minor, and the Etude Op.10 No.3 too.
Others
http://is.gd/sDbntF
http://is.gd/NIdYks
http://is.gd/xGd6iV