Anyone have any ideas on what a slow and great (somewhat romantic) sounding song would be? I want to surprise my girlfriend but don't know what's a good song to play for her. :\

Chopin's Nocturne in Eb major. Nothing else comes up in my mind right now.

Any love song from a movie. I personally like Unchained melody and A Whole New World. A Whole New World might be from a Disney movie, but the song is a classic.

Rurouni Kenshin - Her Most Beautiful Smile

Can't think of anything else, hmm . .

there are plenty out there..
pachelbel canon?

The B section from Chopin's Fantasie-Impromptu

I would suggest a Chopin, or Rachmaninoff Prelude.

Possibly a Debussy Prelude (Bk 1 Nr 8 or Bk 2 nr 5)

The Lyapunov Etude 5 is really beautiful, but i'm not sure what level you're at? it's a bit beyond any other suggestions.

"Sakura Piano version" from Xenosaga 2 is pretty good.

Play the theme for Final Fantasy X (Zanarkand). It's easy, but it always impresses people ^^.

"Aerith's Theme" and "Tifa's Theme" from FFVII are really pretty on the piano. The ones on the Advent Children soundtrack are the best.