Most communication may be by e-mail now but it is still really handy to be able to give someone your contact details when you are away from the machines.
Those chance meetings with people interested in what you do, or just as a way of making sure potential clients/buyers/curators can pick up your info when visiting your exhibitions.
Degree show season is already here and thousands of people will tramp round art colleges, curious to see what goes on there. Many of those visitors are business contacts, gallery owners, curators, collectors and press who find it useful to grab your details so they can check you out later.
One student we know had around 350 cards taken during her degree show last year. Some of them will turn into sales, or offers to exhibit.
Here is a selection of places where you can get quality printing - some for free - some so innovative and 'classy' that they are worth paying for.