There are so many free printable Valentines out there on the series of tubes - here are some of the best. You still have 2 days to print them out. I am going to preemptively give full snaps to Neatorama which is the original source of the first three.

• Bitter Superhero Valentines - get them at Shirt.Woot

• Pun-laden Science Geek Valentines - get them at Neatorama
  

• Pun-laden Science Geek Valentines, the cartoon version - get them at Ironic Sans
  

• Edible Dog Biscuit Cards for your Dog - yikes - get them at Crunchkins

• Anti-Valentines by Dylan Edwards- get them on his site
  

• Disturbing Pimp Valentine's Card - see it at StrangeCosmos