I'm doing some spring (it's spring time in Australia*) cleaning in my bookmarks, that's what I came with:
Genuine Interactive came up with these augmented business cards for its staff, which have been named "the butterfly effect cards". Thomas has dedicated a whole post for their demo.
Visualcard.me on the other hand, lets you create your own AR enabled business cards, that shows your Twitter and Skype accounts.
I'm sure those two companies are not going to be the last ones that come up with this idea, so stay tuned.
* Alas, I'm not in Australia.