A cursory look through any Hallmark store reveals that the greeting card giant seemingly makes products for every possible occasion. From new babies to bar mitzvahs, from first communions to the death of Fido, every life event has its own expression, complete with cloyingly dull poetry, banal photographs, and tired jokes. What's more, between the traditional Hallmark and American Greetings offerings and the racier products at Spencer's gifts, it seems like there is hardly an emotion available or a potential sentiment that hasn't already been bought, packaged, and mass-produced.

On the other hand, one of the marks of a true entrepreneur is his or her ability to find an untapped market, capture its interest, and squeeze it like a juicy orange.

With that in mind, I'm particularly impressed by Three Squares Greeting Cards. Recognizing that the secret of a good card is that it can express emotions and sentiments that are too difficult to say aloud, the manufacturer has developed a line of jailbird greeting cards. The cards are filled with tough-love messages; for example, the Christmas card reads "You had the choice to be 'naughty or nice.' And you chose...Oh well, now you have to do your time. But, Christmas won't be the same without you here. Stay safe. Merry Christmas."

It isn't easy to communicate meaningfully with a friend behind bars. As another card reads "We have not spoken in a long time. I'm ready to start communicating. I'll start by saying, your absence in my life hurts. I love you." Still, with the help of Three Squares, maybe this could become a lot easier. Besides, with more than 1% of America's population currently behind bars, this little card company could be on to the next big money maker!

Bruce Watson is a freelance writer, blogger, and all-around cheapskate. One of his proudest moments was when his littlest sister unveiled her line of deliberately offensive greeting cards.