- Check their web browsing history — Checking your web browser may not give you any juicy details, but it could help you narrow down where your spouse spends their time online (dating sites, perhaps?).
- Monitor their check-in apps — Apps like Google Latitude and Foursquare give you a running tab on places your spouse has checked in at. If they've checked in with a "friend," you'll see their name pop up as well. Now Google her.
- Hack in to their cell phone SIM card — Read cell phone text messages with a little tool called the SIM Card Spy — a favorite among cell phone hackers like Kim Kardashian.
- Get a Video Girl Barbie — Don't act like you haven't thought about using Video Girl Barbie as a spy cam. Everyone has!
- Use GPS — By tossing a GPS device in your car, like the WinPlus Beacon GPS Tracker ($75) you can track your spouse's location on Google Earth, and even get SMS text messages of their whereabouts.