Examples of application, used Android Backup Services

Do you know of any Android applications (open source, if it's possible), which uses the Android Backup Service?

I need examples of how the Backup Service can be used in real applications.

Solution

Here is a list of some open-sourced apps with Android Backup implemented:

Triple Solitaire (github sources, Google Play)
KTodo (github sources, Google Play)
Penroser (github sources, Google Play)
SeriesGuide Show Manager (github sources, Google Play)
ServiceDroid (github sources, Google Play)
Awful (github sources, Google Play)
ConnectBot, Sage-Mobile-Calc (github sources, Google Play)
Headphone SMS, as mentioned by @CodeChimp above (github sources, Google Play)
Dragon, Fly! Free (without source code, only Google Play link)
sms-backup-plus, only source code