Stealth Signal, Inc. is now offering both Mac OS 7-9 and Mac OS X support for its Stealth Signal software, which works in conjunction with its yearly subscription service to track the usage of a computer or laptop, according to SecureMac.com . If the computer is stolen, the Stealth Signal Monitoring Service can be used to track down the computer and work with local law enforcement agencies to recover the stolen equipment. The Stealth Signal service costs US$45 per year for a laptop or $35 per year for a desktop computer.