Valentines themselves are pretty cute, though.
St. Valentinus, while in prison for marrying Christians, fell unrealistically in love with his jailer's daughter and began sending her letters signed "Your Valentine". A tradition was born, one that would eventually resurrect in the hands of blushing, paste-covered schoolchildren.
Here are 7 cute science Valentines, just in time to print off and stuff into those hand-made Valentines reception envelopes made of red construction paper. You make those at work, right? I'm a student, I don't know.