If you are running your Application on Android Emulator (AVD) you can take screen-shots using Eclipse DMMS perspective Screen Capture icon.
Go to ADT Eclipse -> Window -> Open Perspective -> Others -> DDMS -> Look for "Screen Capture" icon at the Right side
Note that your AVD is running, click on the "Screen Capture" icon and you will see a popup window with the image that has been captured with options like,
1. Refresh : when you click this button a new image is captured.
2. Rotate : image will be rotated
3. Save : saves the file with timestamp in file name (e.g. device-2014-10-16-192842.png).
4. Copy : Copies file to clipboard.
5. Done : to close the Window.
This way of taking a screenshot is much faster compared to other options.