Quick Intro to Line2 for iPhone from Toren Ajk on Vimeo.

David Pogue (NYT) reviewed a really cool iPhone app called "Line 2." It creates a second line on your iPhone, with a separate phone number, that runs over VoIP (internet) when you are in a wifi zone, saving precious cellular minutes. It costs $15 a month, but that could be a lot cheaper than paying AT&T for expensive high-minute plans.