I say DOING something instead of BUYING something is a great way to go! Maybe plan a picnic if it's not too cold where you are, or like Cinderbird suggested, a romantic dinner. You could also think of what you like to do together.. Bowling? Putt putt? Hiking? Concerts? Do you write music or poetry or a good artist? Make something special for her. Just make it all about the two of you. If you get her a card, I would suggest adding something to it. Don't just sign your name, but write her a note about how much she means to you are something like that.