See edit section of this post below for updated information.
Check out ShotBot to make lovely screenshots for your app. Here is a quick example of an app I am currently uploading to the App Store.
They have a few templates and I believe they also have an Android template. I definitely recommend checking this out. It is completely free, just sign up with email and they let you create and download for free, no watermarks
Another fantastic option! App Mockup.
Choose from dozens of mock-ups for iOS and Android. It is completely free to use.