The things I find while I'm looking for something else "useful" ... (honest
:-) ....  )

Geocaching. Caches of "trinkets" located all over the world.
Find them using your GPS, take a treasure and leave one in return.
170 caches so far in NZ - thousands worldwide (114 countries).

Some give basic references while others also require puzzle solving to find.

Good user site

                    http://www.brillig.com/geocaching/

Home ?
                   http://www.geocaching.com/

Now, next trip up Tongariro ......

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.