Wait until it's raining outside then go in front of her house at night and play "All by myself" on guitar.
Ok, I actually have a Guitar, I think I should start playing it again.
On another side note, I suggest to those of you that don't have a current gf don't do it, it takes up your life and you're left thinking 'what do I do now' when you realize its gone. But sense it's not exactly 'gone' for me, I'm doing fine.