We had a geocaching birthday party for our two daughters at a park in April. It's like treasure hunting for the 21st Century! We planted two caches ahead of time, full of party favor bags and treats for our hikers.  (Large plastic containers from the dollar store work really well). We hid the caches behind some rocks just off a nearby hiking trail--well hidden, but not impossible for 7 and 8 year olds to find.  Then, at the party, we took the kids (one small group at a time) up the trail, and, using our GPS, we showed them how to track the coordinates of the cache--and where to start looking for it.  There was a special prize for the kid who found the cache in each group. (We used gift cards to Krispy Kreme doughnuts).  The kids were REALLY into the search and had a blast.  Parents were really enthused about our original idea.   Now, after the party, we've turned our "pretend" caches into REAL geocaches that anyone can search for, and on the lids of the container we put a laminated copy of a picture of the kids from the party.  Our daughters love to go check on their "birthday caches". They feel really special knowing geocachers everywhere know all about their birthday party!