I use the multi-image Moo cards, and have a bunch of them out on my table at conventions. They're great. Usually taking a business card is a throwaway thing. But when there's a bunch of different images to choose from, some people will get involved in it, and pick an image that they really like.

Some people just grab the first one that comes to hand, sure. But some people will spend a couple minutes looking at every single design and picking the one they like. Do you know how precious that is in the environment of a comic book convention? Someone is engaged with my promotional materials, in an environment where every square inch is filled with someone's promotional materials.