I'd like to second the recommendation for getting a ham license. Legally carrying my scanner in my car was the sole reason that I got mine!
I knew a little bit about radio communications already; partly as a result of my own curiosity, partly as the result of a scanning hobby I had acquired after some time I spent working for my friend in the Radio Shack store he had been managing at the time. I got the ARRL book, and took the online tests at AA9PW's site
http://www.aa9pw.com/radio/.
Once I was comfortable enough with the material that I could pass the online tests reliably, I went to a test session administered at my local city hall one morning. I passed the Technician test with ease, so I asked if I could try the General test and I passed that one too. (They asked me if I wanted to try for Advanced, but I had seen that material and figured I would be wasting their time and mine.)
It's super easy to find test sessions in your area. Just plug your zip code into the form at
http://www.arrl.org/exam.html.
One unintended side effect of this whole process, I've found myself spending a lot more time eyeballing the inexpensive amateur radio tranceivers in catalogs from Ham Radio Outlet and others. I don't know why, I really had no intention to transmit when I took the test, but the more I read on this forum the more interested I seem get. (Just what I need, another expensive hobby!)