I found Moo a few months ago and love'em. "We love to print" is their motto and they live it every day. I've received more oo's and ah's over our business minicards than you can believe. Plus, they are easy to use and the customer service is fabulous.
They've recently come out with mini-Love Cheques. (They are British so please lay off their funny spelling.) I think this is a wonderful idea. You can purchase a pack of 100 for $19.99 and give them to your loved one to use as s/he sees fit. The ideas range from "Old Fashioned Date" to more risquee (but completely legal) ideas.
You can even customize the cards. You know, like add a "You may only use this card with me" or "Must allow for at least 30 minutes but no more than 5 days to expect fulfillment" disclaimers. And you don't have to give them the entire stack of 100. Give them a few and see how things turn out. You can always provide a few more down the road.
The mini-Love Cheques are one of the better, fun ideas I've seen in a while for the dreaded V-Day. Enjoy!