It depends on many factors, including your financial situation, your preferences and your relationship with your significant other.

WSJ: Ask Ariely: Dan Ariely on Hot Wheels to Close Big Deals

There's the nice addition of some metrics between you and your phonebook, visualizing that precarious balance between text messages and calls with your significant other -- or a timegraph of when you call Mom.

ENGADGET: Current Caller ID app adds social info, weather details, suggests a good time to ring back