Last summer, Ali Wise, a celeb-hobnobbing fashion publicist, was arrested in New York City and faces charges that include alleged harassment and stalking after she'd hacked into the voice mail of her ex-boyfriend's new girlfriend. Her techie weapon of choice? SpoofCard, a subscriber service that allows you to call someone from your own phone but trick their caller ID into displaying a different number. Wise allegedly phoned the girlfriend using SpoofCard, then programmed the girlfriend's own number into the caller ID, as if she were calling in for her own messages. SpoofCard—whose business spiked by 200 percent last year—was designed to help bill collectors track down clients with past-due IOUs, says cocreator Meir Cohen. But, he admits, "It's most popular among people in relationships where there's suspicion of cheating." Cohen says his company doesn't monitor how people use the service. "But we do cooperate with law enforcement when our records are subpoenaed, as in the case for Wise," he adds. With a price tag of only $5 for 25 minutes and apps for BlackBerry and iPhone, SpoofCard is a stalker's cheap-and-easy dream tech, and makes hacking into your ex's e-mail seem almost quaint.