AirportMap - Best way I have found to locate an airport at a given destination.
SocialFlight - Good way to find places to fly or things to do.
Flightradar - For tracking where my kids are flying/when they will be home
FlighAware - Same as above, but includes some 978mhz flights.
The Moon - Helps me plan flights based on moon visibility. - I like to have some moon light if I am flying at night to help me see and avoid clouds.
FlashPass - for easealy filing customs clearance for international flights (Canada, the Bahamas, Mexico)
ForeFlight - Cant Fly without it, even locally so I can check TRF's without a 15 minute phone call to Flight Services.
Weather - I use the standard Apple weather app to predict weather for upcoming flights.