It's my new hobby.
A few of you have asked about it so here's a brief description.
Essentially it's a global treasure hunt in which participants use a hand-held gps unit to find "caches" hidden all over the world. The basic idea is that individuals or groups set up caches and then log their coordinates on a website - www.geocaching.com Members then programme these coordinates into their gps unit and go off and find the cache. A cache at its most basic will be something like a 35mm film canister with a logsheet in it. You sign and date the log to confirm you've been there and then log your find on the website. Larger caches contain "swaps". These are generally small, inexpensive items like small toys, puzzles, hair clips, anything really. I'm famous for leaving glow in the dark yoyos in caches. The idea is that if you take something from a cache you leave something too so that there is always a few items for the next person to choose from.
That's it really. You go out and look for things. But - speaking personally it's got me out into the countryside and I have discovered that I live a few minutes from some truly beautiful areas. I've seen wild orchids growing, pheasants wandering about, day old lambs, all sorts of wildlife and beautiful scenery. And I've lost a bit of weight. :D
A dog is not compulsory but they enjoy the walks too.
If you want to see if there are any near you go to www.geocaching.com and click Hide and Seek a Cache. Put your postcode in the Zip Code box and it will search the nearest ones out for you. There are 930 within 20 miles of my home address.
There are also virtual caches which involve you getting your photo taken at a particular coordinate - there are several of these inside WDW. :D