We nearly always forget to carry business cards and we may not be alone in this. InTooch is an iPhone/Android app aimed at making business cards unnecessary.
A common way to save a person’s contact information when they don’t have a business card is to ask them to call you on your cell phone. (But we usually forget to carry a cell phone as well.) That call would give you their phone number, but nothing else. When you call someone using the InTooch app, you get a wealth of detail, including their name, address, Facebook, Twitter, and LinkedIn info. The other person doesn’t need the app installed for this to work.