Sporty's E6B Sporty's Pilot Shop: $4.99 (introductory price)
Sporty's E6B iPad-based flight computer does everything a steel wheel E6B does, and it does it faster and way more accurately. It features 23 aviation functions, including actual true airspeed, crosswind, headwind and tailwind, weight and moment, and many more. Well, 20 more. You can also do 14 aviation conversions (Celsius to Fahrenheit, for instance), and it features a calculator and the world's largest count-up or countdown timer.