For TED I didn't want to give out only business cards from work because they have my work email and phone number on it, and they also don't have my email, website, or blog on them. In general it seems like a good idea to have some personal business cards for random people you meet, people you might want to keep in touch with but you'd rather they email you at home rather than call you at work :)
Anyhoo after some research I decided to keep it simple and go with moo.com. A friend showed me their "MiniCards" a while back and they were really effective. I went with the normal-sized ones, but opted to upload my own images - an assortment of photos I've taken on trips (from the "best of" album I chose for my new website.) It'll be nice to have these for the conference and beyond.