Most of the lawyers in my office were just at an annual two-day seminar. (I didn't go: I stayed behind in the office and consolidated my upcoming power grab. And ate pizza.)
They came back armed with business cards from other lawyers, cards they gave to me because those other lawyers wanted to talk to me about various cases. Since I wasn't there, they'd handed off a card and gotten the message to me.
That's what business cards do for you: they serve as a message, a reminder, an introduction, a placeholder. In the world of email and websites and blogs, business cards are an inexpensive and still effective way to get your foot in the door and keep it there.
They're not just for office-types, either. Whatever your profession, a business card is like a little advertisement you can get someone to carry around for you. Consider the business cards for photographers you can buy from Face Media Group. They're full colour business cards that pack a pretty good wallop of advertisement -- sending a message about you and your services and skills, all for about 20 dollars a set.
I'm never without my business cards. I go for the plainer kind -- white, my name and firm and contact information, a little bit of color in the printing -- because I figure it fits the kind of image I want: Not flashy, but dependable and safe. But you can go any direction you want: Laminated, thicker (and more solid, safe seeming?), even recycled-- people in eco-businesses will be able to use their cards to show how they care about the earth. You can even get double-sided cards these days, with a cool image on front and your information on back.