Fran's got a fantastic twist on handmade cards:
Type Valentine's Day phrases and symbols in a Word document in various colors – with the line-spacing set at 2-3 inches apart. Add images of the kids' faces and crop or size them down to 1-2 inch photos. Print out several copies of the document on office supply (I used Staples') matte sticker paper, using a color printer. The sticker paper has a crack-and-peel backing that stays on until you're ready. You can cut the images and words apart and keep copies of each in piles or in plastic bags on a work table.
My daughter picks some stickers from each bag, peels off the back (sometimes with help) and places them on colored construction paper "cards" we cut and fold ourselves. She loves stickers – and putting her own face and words on a card for Grandma makes everyone happy. We keep the leftovers for the next year – and sometimes use them to seal letters and gifts.