Eric Cronin found this cute little junior phone bugging kit on sale at Toys 'R Us. Recommended for ages 10-14 (presumably because children any older than that are more likely to be prosecuted under 18 USC 2511 and 18 USC 2512), the kit is basically a tunable low-power FM radio transmitter designed to connect to an analog telephone line. I especially like the way the instruction sheet [pdf] prominently warns of the dangers of eating solder, but only casually mentions the illegality of listening to other people's phone calls once you've got the thing built. (A non-trivial concern, especially considering the trouble that Ramsey Electronics got into with the US Customs service a few years back for selling similar kits.)
As strongly as I feel about the evils of illegal wiretapping, I must admit to having decidedly mixed feelings here. No, kids, don't tap your neighbor's phone. But unraveling the once-forbidden mysteries of telephone electronics has a way of pulling a young geek into a lifetime of technological exploration. It certainly did for me.
I was at a conference recently where everyone was asked to recall their first moment of thinking "I rule!" over some technology. It's a surprisingly revealing question; experience the exhilaration of hacker empowerment at a sufficiently impressionable age and you're hooked forever. A disproportionately large fraction of the answers seemed to involve telephony. (Mine was when I discovered you could dial a phone by flashing the hookswitch. I think I was too young to have anyone to call, though).
So I suppose if the nerdy kid next door figures out how to hook one of these kits up to my phone, I won't be too upset. Just make sure not to eat the solder.