I ask this question after receiving hundreds of business cards from attending an event in Atlanta GA called Industry Day. As I was going through my pile of cards to follow up, I realized I couldn't get in touch with close to one third of the people who ASKED to be contacted! Why? Their business card either had no e-mail address, no website or was in another language...I kid you not.
Bottom line, business cards are meant to make a connection, to allow others to know a small piece of information about you and your business to ultimately make a relationship and hopefully, a sale somewhere down the road. If your new contact has no idea how to get in touch with you, you have just closed all roads to making a potential business relationship in any form or fashion.
If you're on Active Rain, you know the power of networking. Don't think that power doesn't exist outside the internet. Good old fashion hand shaking and card exchanging may be "old school" but it works :-)