There are free and paid smartphone apps. The free apps will satisfy all your needs but you have to bear with a bunch of ads that can be annoying at times. The apps below, even though are expensive, are actually worth their price.
XCOM: Enemy Unknown
This is one of the best games on iOS or Android. It costs $10 and is a full game with modified controls for touchscreen. There are no micro-transactions and no ads with this app.
SkySafari Pro 4
SkySafari Pro is very pricey but is a one-stop-shop for any amateur astronomer.
This is great for playing at home and experimenting with different effects and also for recording. If you need it you will have to pay more than $150 for everything.
This is great if Yahoo Weather doesn’t cut it for you. You will spend about $10, but that nothing if you are meteorologist or if you are keen on matters weather.
Go for White Noise if you need some good sleep. With this app you can set any sound you want to help you get satisfying sleep. You can even blend up to 4 sounds together. Those who have used it say they would be willing to pay even ten times its cost!
This is great for reading the Check Engine codes and data logging. It costs $4.95 (Android) plus a $25 dongle to go with it.
This is an Android application that performs tasks based on contexts in user defined profiles. It extends yyour control of your Android device and its capabilities.
This is the best task management platform around. It will help you manage your life, work, etc.