No good can come of this, but if you're in need to a quick and unreliable way to test your spouse's fidelity, then the $US8 Agile Lie Detector for the iPhone might work.
Allow me to repeat myself. No good can come of this.
The Agile Lie Detector uses voice stress analysis to judge a speaker's words in real time. And while you admire the 3D spectrograph with no real clue what it means, a simple "lie meter" will indicate just how much your kids really like your chili, your mum didn't mind changing your diapers or your wife...well...that woman is a saint just to be with you. Maybe you DON'T want to know if she's just in it for the chili. Maybe you should just take her smile for what it is, a smile, and be thankful it's there at all.