DO AHEAD:

Confirm Airline Ticket
Arrange transportation to/from airport
Arrange pet sitting
Buy plenty of pet food
Get money/travelers checks
Pay mortgage/bills that will be due
Hide valuables
Do laundry
Iron
Clean house
Take out garbage
Leave phone numbers with someone
Tell tenant I'm out & leave number
Notify neighbors if packages are expected (or leave note for UPS)
Empty car of valuables if leaving @ airport
Change cat litter

LAST MINUTE

Leave pet/plant instructions
Fill pet food & water
Close blinds/curtains
Cover couch?
Close bedroom door?
Leave light on
Leave house/mail key with house sitter
Water plants
Adjust/check answering machine (change from 4-auto)
Run dishwasher
Turn heat down
Run water if freeze is possible
Turn off water to washing machine
Make sure home is pet safe (wedge open doors)
Bring food for flight if necessary
Check windows & door locks