How to back up an Android application to an .apk file on your source Android device
To back up applications from one Android device and side-load them to another, begin by opening the Android Market and downloading "Astro File Manager."
Once you've downloaded Astro File Manager, open the application.
In Astro, press the Menu button on your Android device and select Tools.
In the Tools menu, select "Application Manager/Backup."
Astro will load the list of your installed packages. Check the file(s) you want to back up to side-load to another Android device. Select the "Backup" button. A status bar will display the progress of the backup.
Once the backup is complete, select the "Backed Up Apps" tab to confirm that the files you selected were backed up.Copy the .apk file from your source Android device to your target Android device.
Donovan Colbert has over 16 years of experience in the IT Industry. He's worked in help-desk, enterprise software support, systems administration and engineering, IT management, and is a regular contributor for TechRepublic. Currently, his professional role is as a Linux support engineer for a fast-growing Linux/FOSS consultancy group. You can follow him @dcolbert on Twitter or his personal blog, located at http://donovancolbert.blogspot.com.