Typical conversation while taking pictures:
Random bloke: Are you a professional photographer?
Me: No, I'm just an amateur
RB: Oh, what do you do with the pictures you take
Me: I publish them on my Photostream on Flickr
Me: On the internet
RB Oh, what's the address?
Me: Do you have a pen and paper?
---Either they do---
I give them my address which they lose
---Or the don't---
I give them my address which they forget
I was goingt o buy Moo cards, but they were too expensive, so I printed a whole bunch myself and used wood glue to stick them on one side to a piece of cardboard... now I can give them out when people ask, and I just tell them to put it in their wallet.