I browse a lot of design blogs and have almost overdosed already on all the hearts and pink everywhere so I'm not going to go overboard on the Valentine's themed posts. This however is a really sweet and easy piece of origami that you can make in a minute or so. I found the tutorial on youtube (that's the absolute best way to learn origami in my opinion) and the photos are of a few hearts I made myself.
If you search on youtube you can find slightly more complex versions of this design with more realistic wings but I think this one is a good one to start with if you haven't done a lot of origami before. You could make large versions of this to decorate a room or stick one to the front of a homemade Valentine's card.