If you have kids that are old enough to walk and enjoy a good treasure hunt, you really ought to look into Geocaching.
According to their own website, geocaching is an entertaining adventure game for gps (handheld global position system/ the techie compass) users. Participating in a cache hunt is a good way to take advantage of the wonderful features and capability of a gps unit. The basic idea is to have individuals and organizations set up caches all over the world and share the locations of these caches on the internet. GPS users can then use the location coordinates to find the caches. Once found, a cache may provide the visitor with a wide variety of rewards. All the visitor is asked to do is if they get something they should try to leave something for the cache.
We were introduced to Geocaching (pronounced Geocashing) by another homeschool family. All you do is go to the Geocaching website, type in your zip code and it will find all of the geocaches in your area. We were so surprised to realize that there were these little hidden treasures all over our little area. There isn't really anything valuable in the caches. The little trinkets that are there are more just mementos of a fun experience. You can register with the website and then keep a log of everything you've found and then you can even begin hiding some yourself.
We found our first few without a GPS. We just read the online clues and started looking. It was so much fun. Like blogging it can be quite addictive. You can search for caches anywhere you are traveling and hunt for them there as well. Most of the caches we've found were hidden in off the beaten road kind of locations that were pretty nice to find anyway. We've only ever been stumped (not able to find a cache) once and we even met another geocacher looking for the same one on that day.
It's a lot of fun. So go check out the Geocaching website, get out there and hunt!