Paper valentines never worked very well for me. They're either cutesy-sick-lovey-dovey or they attempt to be "naughty" in the British sense. So instead, I tend to write messages in the sand or snow to my valentine.
This was a big one I wrote a few years ago, and was scanning a bunch of old pics and found it. Devil's Lake State Park, about 10-11 years ago.
Now that we have the canvas and the proper medium, get busy people. Send messages to your loved ones and break out the digital cameras. If you live where it's warm, a beach at low tide is perfect for your expressions of love and affection.