Online business cards. A site where you can create your business card, choose from many different designs, upload your company logo, customize the design, add links to your [choose your favorite online service] account, etc. Something like this: http://rogieking.com/ but for everybody.

Then you could have private and public information. You could share your private card via invitation or a special code, you could also share your card via sms, facebook and a phone app (iphone, bb, palm pre, etc).

You'd also be able to choose a print design and order some prints (possible partnership with Moo?).

I have a few more features in mind, like click-to-call and other stuff, but I guess you get the idea.