Visit your local museum (many have a “free day” after a certain hour of the afternoon if you call ahead to check which day of the week).
Give her a kiss on the cheek.
Make her a car emergency kit with flashlight, umbrella, flares, blanket, etc.
Next time you notice a free sample somewhere – the mall (perfume), grocery (a new product) – grab one from her. Gifts don’t have to cost anything to be thoughtful.
Tell her today your favorite part of her physical looks – her eyes, hair, figure. Don’t be leering, just genuinely admire her beauty.
Take a train ride.
Paint her nails (or toenails) for her.
Wash her car for her (and vacuum it clean on the inside).
Enroll her in an adult education class in a topic she’s interested in. Cooking, literature, check with your local college.
Sing her a song – even if it’s off key, pick one with romantic lyrics and she won’t even notice.