Tiny Prints

Tiny Prints is a greeting card publisher that accepts unsolicited submissions for a variety of occasions.  They use three main styles of cards: sentimental, simple, and humorous.  They have detailed guidelines for how they want submissions to be formatted, so be sure to read the complete guidelines before sending in your ideas.  Tiny Prints pays $15 per accepted idea and they generally respond pretty quickly.  These guidelines come courtesy of WritersWeekly.