To enjoy nature of course!  Recently we kept the cute little urchins that are my nephews and niece.  These are your typical children of 2009...they prefer to play on the playstation to going outdoors.  The end.  The children are a 7 year old boy and  a boy-girl set of 5 year old twins, the perfect age to get involved in nature.  They already love animals, hence the mysterious disappearance of my cat for the duration that the children are visiting.  Generally I plan lots of activities to keep them occupied and away from aforementioned playstation for as long a time as possible.  This last time we had them we decided to introduce them to geocaching (check out geocaching.com if you aren't familiar with it...very cool activity and totally fun for all ages!) but alas we had some technical difficulties.  The end result was a nice long hike in the woods that at least got them outside and picking up rocks and leaves.  We also collected pine cones for the infamous pine cone bird feeders, but as the weather was not so preferable to letting them peanut butter and bird seed the pine cones outdoors and I couldn't possibly stomach the thought of cleaning peanut butter off of every surface, chair, carpet, computer, toilet, window, cat and anything else that would  have inevitably come into contact with 6 busy hands, I decided to forestall the execution of this plan for the next visit!  Now I will have another reason to get them out of the house the next time we keep them!