WACK ARM

If you are developing Windows 8 Store apps you should really test those on low-powered x86 and ARM devices. The difference to your high-end x64 developer machine can be dramatically, esp. if you use a non-default design.
Testing on ARM is important and Tim Heuer wrote a nice post which shows how to remotely deploy, debug and profile on ARM devices right from Visual Studio 2012. Another nice thing which performs a couple of automated tests is the Windows App Certification Kit (WACK). Unfortunately is the WACK tool for ARM hidden inside the Windows 8 SDK, but here's how to find it:

1. Download the Windows 8 SDK web setup from here and run it.
2. Choose to download the SDK files for offline usage.
3. On the "Select the features you want to download" screen it's enough if you only select the "Windows App Certification Kit" checkbox.
4. After the download is finished, you will find an "Installers" subfolder in the download target folder.
5. Copy the "Windows App Certification Kit arm-arm_en-us.msi" from the "Installers" folder to an USB key or SkyDrive.
6. Open the "Windows App Certification Kit arm-arm_en-us.msi" on your ARM device and install the WACK on it. 
7. Search for "Windows App Cert Kit" on your ARM device using the Search Charm and run the WACK.