Cool or immortal valentines
There's a Simpsons episode where Lisa gives Ralph a valentine that reads: "I choo choo choose you!" (A good Simpsons fan will always get a big kick out of this!)
There's also the geek special of:
Roses are #FF0000
Violets are #0000FF
All my base
Are belong to you.
What are some other nifty/timeless/silly valentines or valentine sayings?