Make her something. One year, I bought a bouquet of red roses, chopped them up, used the stems as a frame, and super glued or strung the rose petals (and rose flowers that just had their stems chopped off, onto the frame. Then I glued the frame to another frame that I had pasted a Photoshopped image of a beautiful field of red flowers that matched the roses and used a program to write a poem on it. Then I took the creation, put it in a big box, and wrapped a red ribbon around it. She loved it and kept it on her wall during our entire relationship and treated it like gold. Nothing says I care then taking the time to make something heartfelt.
Another time, for fun, I liked this girl so I made her medal. She worked really hard at her job but wasn't recognized, just criticizred. So I got two balls of yarn and strung them around a round piece of medal until all you could see or feel was the the pink and yellow (her fave colors) yarn. Then I cut letters (like actual letters i, e, t, y) out of a magazine and super glued them onto the medal saying employee of the century. It just showed that someone acknowledged and admired her hard work.