Directed Spy Microphone. Very cool website as well. Lots of neat stuff!
The Invisible Bluetooth Earpiece SPY Kit for Students - YouTube
How To Make Spy Microphone! Super spy microphone made from plastic parabolic dish,old game fun for handle and earbuds with mic and all this work on your smartphone.
What is an op amp? Operational Amplifier tutorial super spy microphone circuit
Make your own Parabolic Microphone: http://mods-n-hacks.wonderhowto.com/how-to/eavesdrop-from-distance-with-diy-parabolic-spy-microphone-0139405/
Mengshen® Highly-Sensitive Mini Spy Microphone Audio Ear ...**Click Image for complete Information**
Weekend Projects - Squirrel-Baffle Spy Microphone
I need to build a laser microphone like this! Not to be a creepy spy, but just for the challenge.
57% Off CCTV High Sensitive Spy Microphone Audio RCA Security Camera w/ Power Cable 3UB - eBay Daily Deal! - #priceabate! BUY IT NOW ONLY $29.90
Eavesdrop from a Distance with This DIY Parabolic "Spy" Microphone « Hacks, Mods & Circuitry