When I build websites, I often get a set of free business cards from VistaPrint. I'll pass these around to people so they'll remember to try my new site.
VistaPrint will send you 250 cards on good quality paper for free. You only have to pay shipping - which is under $6. It's cheaper and easier than printing them yourself.
The problem is that VistaPrint offers 42 fairly mediocre designs for the free cards. I prefer simple cards, often with a white background.
Here are the 6 templates I currently like best. I'm not saying these are great designs, but they do the job just fine, and they're basically free.
If you click on these, it'll take you to vista print. The page number under each card is the page the specific template is on in the VistaPrint "Select Your Design" form. Fill in your info (I often leave fields blank, and just put the URL in the main name location) and get some free cards.
UPDATE: The New York Times covers VistaPrint - it's an impressive business model:
A printing company that has strung together 28 profitable quarters by selling — and giving away — business cards. The free cards, of which VistaPrint has distributed 2.5 billion, carry the company’s marketing message on the back.
The article describes how VistaPrint uses software to batch orders together and reduce costs by 50%. Knowing how well they measure and optimize online conversion, it's not surprising that the business is based around software optimization of a business process.