The OP asked for input from law students and attorneys. I appreciate the fact that law students who are offering advice may have different opinions. I am an attorney and I would honestly think that a law student who had a "business card" was desparate and ridiculous. If I meet you at an event and you want to follow up with me, giving me your card is not going to help unless I want to follow up with you as well. If I want to follow up with you, I will give you my card. I cannot remember ever being in a situation where I wanted to get a person's contact information but was thwarted (or even inconvenienced) by the lack of a pen. I certainly would not think any better of a person who had a business card.
i agree with ajude. my law school offers them and they are tacky. they make you appear to be a "networking whore". picture this...you are at a fancy party with numerous attys. you strike up a very stimulating and meaningful conversation with one of them. at the conclusion of the exchange, he/she asks if they can have your email/phone number, so you can talk again sometime. well...."have no fear...i have a business card on my person for times like this!!". it makes you look like you engage in conversations with people, in order to use them for any profesional benefits they can offer you. its like constantly carrying around condoms in your pocket. people think you just want to walk around and get laid.