Not a new idea, but I tried these valentine's out this year and they got RAVE reviews. Not only are these such a cute idea, but they will always be unique since the child in the picture is unique. I'm hoping we can do them each year and compare. We also realized that it is nice for the young ones that can't write yet, in they don't need to be "signed" by who its from.
Simply take a photo of your child holding out a fist. You can add words and hearts before printing (like I've done), or have your child decorate after with stickers, etc. Get 4x6 prints made, then punch the top and bottom of the fist. Insert a sucker and you've got one adorable valentine!
This "Despicable Me" minion box for cards was made from a large Kleenex box. All it took was construction paper, pipe cleaners and toilet paper tubes wrapped with aluminum foil for the goggles. The best part is beyond Valentine's Day, it becomes a wonderful play thing for my kids.