Micronic Ruby Miniature Radio
Okay, so I'll admit that I have a big gorilla hand, but honestly this is a really small radio. The Micronic Ruby dates back to the mid sixties, and is an amazing achievement in miniaturization. The radio features eight transistors (how'd they fit 'em all in there?) and a built in speaker (impossible!). It uses mercury laden batteries, and has a weird earphone plug, so I've actually never heard it in action. It was an expensive item back in the day, usually packaged in a velvet lined jewelry box.
Micronic made several models, but this is among the smallest. Expensive then and still expensive now, expect to pay $75-100 from a collector. I've seen them on Ebay & antique shops around the $30-40 mark, or you can just dig around in the toy section of the thrift where I found mine for $2. :)