OT - what are your favorite smartphone apps?

There are thousands of apps out there. What are your favorites and their cost?  Most of mine are free.  Post yours up and why, whether for cooking, fishing, golf, gardening etc... Post them up and at least one reason why it is one of your favorites.  

Navionics US and Canada - $19.99 - it is like the full  boat plotter in my hand.  Geocodes pictures taken on the map. Invaluable as a backup when on the water.  Can estimate fuel burn and ETA as well as depth. 

ShralpTide - free - tells me the tide simple and overly easy.  

Waze - free - driving directions.  Will route me around traffic, and alert me to cops and other hazards while driving. I bet most people have this by now. 

Convertbot. - free - will convert the most common measurements from one to another.  Miles to inches,  days to seconds, standard to metric etc...

Accuweather - free - all weather information you need.  Predicts rain to the minute, and will alert you. Just found this one last week and am learning it now, but am impressed so far. 

Asana - free -  for task tracking.  Mobile version is as good as the web app. Keeps me updated when I need to be.  Organizes all my tasks. 

Starchart - free - for the 1% interest in astronomy I have, this is sooo cool. Point the phone at the sky, and you can tell what star or plant you are looking at, if it is part of a constellation, and how far it is by tapping the screen.  Really cool to use with your kids or when out I the middle of nowhere and can see a bunch of stars.  

What are yours?