Let’s not get into the legality of this device. But if you have a need to listen in on conversations for whatever reason, the Spy Bug Audio Surveillance gadget pictured above should do the trick. About as small as a pack of matches, it accepts a SIM card, which means you can just call it anytime you want to eavesdrop. Better yet, you can set it so that anytime there’s a sound above 45dB within 10m, it calls you! $60
