Instead of business cards, I think having small flyers or small-sized prints work best for advertising for a comic or singular project. It could be like your cover is printed with a couple links to your comic or other blog spaces related to your comic. That way, somebody can see your art firsthand and get excited about it. Then they look for your links on the flyer.
I think business cards are too small for what you want to do--at least, to me. I'd prefer a comic artist hand out a small paper with something exciting/intriguing on it and not just a card with the link to their comic.
OR, here's an idea! If your comic is character-heavy, you could do something the size of a bookmark with a different character on them. Hand them out with your wares for free, or have them spread on the table as a free-to-grab item. Then people can: see your cool characters and art, have the links to your comic/sites, AND be able to use it as a bookmark. :}
