Paul King was headed to the airport in Pittsburgh in 2006 when he suffered an ill-timed communications blackout. His cell phone died -- and the Carnegie Mellon student realized he still had his roommate's house key in his pocket.
If he didn't call her to arrange a return, she would be locked out all weekend. But without access to his electronic phonebook, he didn't know her number.
Cell phone dead? Hercules Networks will sell you a charge - Jan. 29, 2010