People don't just use BlackBerry; once they've discovered it, they can't live without it. Though it can be used as a phone, the BlackBerry's power lies in its ability to push email automatically from the company server to the end user. That simple concept has <A HREF="http://www.cnn.com/2005/BUSINESS/03/23/blackberry.rim/index.html">revolutionized corporate life.</A> Two million BlackBerry subscribers have already signed up and their numbers are growing rapidly.