The easiest way to create apps for your phone!

App Inventor is built on the idea that you do not need to be a
developer to build great mobile applications. Instead of code, App
Inventor allows you to visually design applications and use blocks to
specify application logic.

Use the GPS-location sensor to build location aware apps
For example, build an app to help you remember where you parked your car.
Make your apps communicate by using the phone functionality
For example, build an app that periodically texts "missing you" to your loved ones.
Integrate with the web to build mashup applications
For example, build an app that talks to your favorite website like Twitter.

Check out here