One of our favorite things to do is geocache while we travel - we get to see lots of interesting spots off the beaten path I'm sure we would never have seen had we not been hunting a cache. Although of course often times there are caches at the big tourtist spots too. In fact I forgot to mention in my post about the Nubble Light that there is a cache there that we found. Not gonna tell ya where though! :-)
One of the interesting places we stumbled upon in our geocaching travels was John Hancock's Wharf in York, ME. I had no idea York was so rich in history, nor did I have any idea John Hancock lived there.
Another stop brought us to Herbie:
We saw where the first permanent settlement in Wells was in 1640:
And we found this great duck/geese/swan pond - we had so much fun there we went back again the afternoon we were leaving just to feed them one more time:
I would normally say that once you've bought a gps (I looked and you can get a basic one for as little as $92 at Amazon - see link in sidebar) it's an inexpensive hobby. However with the price of gas, I can't really say that anymore. But, we often combine geocaching with trips we were taking anyway, so that lessens the cost. And adds to the fun! :-)