How do you prefer to trade information? Business card (only to be scanned later)? napkin? bumping?

For online professional business networking, LinkedIn is still the gold standard. It recently topped 70 million users and has been adding a ton of new features including: deep twitter integration allowing you to follow your linkedin connections privately, tracking movement in industries by seeing recent hires and departures at specific companies, and integration with Microsoft Outlook.

This free LinkedIn iPhone app gives you access to much of the functionality of the site, allowing you to update contacts with your status, send invites, accept invites, message, as well as connect instantly with nearby LinkedIn app users with the “In Person” feature. Download the app for the iPhone here. LinkedIn also offers free apps for the Blackberry and Palm Pre.