Here is my second attempt at making a chalkboard printable. I downloaded the chalkboard backgrounds from here. I put mine together in Photoshop but you can create it in Picasa just as well.
Simply open the chalkboard background in the color of your choice, then add your text on top. For Christmas I got a Samsung Note and absolutely love it. I wanted to have a bit of a hand drawn element to this one so I used the note to draw the heart. After a little bit of photoshop magic I was able to remove all the background and change the color to pink. If you would rather, you can download mine and print so you can add it to your own Valentine decor.
This is a 8.5"x11" so you can 'shrink to fit' if you are printing it to a smaller size. Enjoy!!