Titanium Backup is one of the must have Android application. You can backup and restore application, data, setting with it. A great tool for me who like to test several Android builds. However, it is for rooted phone. But it is not a problem for me as most of the Android builds for HTC HD2 are rooted.
![Titanium-Backup](https://www.jayceooi.com/wp-content/uploads/2010/11/Titanium-Backup.jpg?x67711)