I get a lot of questions from photographers about "Business Cards". If you are doing any kind of paid work, you need to have something quick you can give to a potential customer, but my take on it is this:
Whatever you give them, it must be so special they will never, ever want to throw it away.
What I personally use now are custom 16GB thumb drives with my website logo on it. (Michael's Custom Thumbdrives
Simple, but very sticky and it has enough info on it that they can always contact me. While they are a bit expensive, most appreciate a free thumb drive, especially one with extra storage space.
That said, you do not need to spend a lot of money to be creative with your design, Flavorwire.com
has compiled some pretty unique business cards that are sure to keep anyone who gets one to remember the business. Some of these are super creative: