I just got a batch of 100 minicards from Moo.com and I'm in love with them. They're two-sided and they have one of seven designs in the front (a black background with white lettering that says 'left is right,' 'right is left,' 'out is up,' etc) and my information on the back. I've handed out a handful and they've gotten great responses. They're just different enough and clever enough to be memorable without inducing groans and eye rolling.
I think for my next batch I'll include a QR code linking to my LinkedIn.com page.