Perhaps this is baked..
You can now buy a hollowed out coin that can hold an 8 GB Micro SD Card.
They need to be augmented with a small battery, RF transponder (for reading/writing data), inductive charger, and, of course, circuitry to do voice activated recording (and maybe GPS logging). Bonus if the charging can be done through harvesting kinetic energy, like some watches.
These could then be released into the "wild" and record all sorts of interesting conversations, and be gathered later to be "harvested."
The problem is, now I'm paranoid that someone else might have implemented this idea already. All my change is going in a soundproof wallet!-- cowtamer, Mar 12 2010 Hollowed out coin http://www.thinkgee...ols/b308/?cpg=wnrssAdvertised as spy gear... [cowtamer, Mar 12 2010] Almost... http://www.spysource.net/micox18.htmMicro-X18 coin-sized recorder with Voice Activation System and 18 hour recording time. [jurist, Mar 12 2010] *pulls the handle on the slot machine* Jackpot! coins galore all saying "we're free" "viva la revolution" "are you my mommy?" lol-- Arcanus, Mar 12 2010 "I am Keyser Söze !"-- 8th of 7, Mar 12 2010 Random bugging. I like it.-- wagster, Mar 12 2010 random, halfbakery