The Rules of the House: Before you leave...
wash and DRY all towels and sheets (don't leave wet stuff in washer -it will have to be washed again, and don't leave dryer running when you leave - it's a fire hazard)
take out trash and recycling
do any dishes in the sink
start dish washer
sweep floor - ESPECIALLY in dining room and kitchen (you don't even want to see how many ants come running after a couple crumbs)
close & lock all windows
close & lock all doors (including garage padlock)
** check that laundry room toilet is not running
and if you really want to be nice...
leave some beer in the fridge for the next guy :) (this is optional)