Lovestagram is a brand-new Instagram plug-in that lets you make Valentines from your Instagram photos. It's very neat, but the best part about it is the back story: the very site itself is a Valentine's Day gift.
Lovestagram lets you apply heart-shapes, pink cameras, or candy borders and greeting text to Instagram photos that you share with another person. (It has to be somebody whose Instagram photos you've liked or commented on, or vice-versa). It kicks out a nice little Valentine that you can send via email. Aw!
But what really warms my heart is that the site was built by the girlfriend of one of the company's founders. Kaitlyn Trigger not only built the site herself, she even learned to code to do so.