I hate to say it but mine has already saved me more than it cost.  When I upgraded my phones I signed up for a new two year contract.  After the dust settled I was actually a couple hundred dollars ahead.  I paid $300 to upgrade two phones & have two $100 mail in rebates in process.  Then my carrier shot me a $300 thank you for re-signing since I'm a long time customer.
Not two weeks after I got the BlackBerries I got a phone call from a local business that I frequent.  The sales person I always deal with called me on a Saturday evening & said they had a fantastic deal but I would have to move on it that night.  I was out of state at the time but I was able to use the phone to transfer money from my savings account to my checking account so that a debit transaction could be done.  That transaction saved me a couple of thousand dollars.
(Before I get lectured/flamed too bad.  

  I don't plan on doing banking from my phone in the future since I seriously doubt that's it's very secure but it's good to know that it's possible in a pinch.)