To stand out from the crowd and to be different some persons do something like they put on some clothes that would express their personalities or make a tattoo or something. Same way in design too some people like to be different , so that they find ways to impress their viewers with different creative stuff they make. It also helps to promote the business.
Here is a list of mini business cards will inspire you to create your own size and design and impress your future clients.
If you are creative enough you can definitely find your own ways to do that. The perfect choice would be miniature business cards. These are not so common anyway and you can really stand out from the crowd by having them. Once you choose to have mini business cards, you have to think of the perfect design that would be right for them, in order for the right information to fit in.