A new Live Tile showing your device's battery level has just been released on the XDA Developers forum. Because of limitations on regular Windows Phone applications, it requires an unlocked device, which can now be easily done via the ChevronWP7 service. If you've been closely monitoring your device's battery level, you'll know that indicator in the Windows Phone status bar isn't too helpful. If you need an actual percentage level, you need to go into the settings menu and find the Battery Saver page. Instead, this battery status app will give a periodically updated percentage reading directly to your start page.
This is of course going to serve a niche group, whom will not be put off by having to perform a device unlock. While some people are just obsessed with stats, it will be most helpful to those who are reviewing and benchmarking, or troubleshooting, a Windows Phone device. Indeed, I have been taking regular battery readings of a device I'll be reviewing soon, and this would have been very helpful to me.
If you want to find out more, watch the embedded video, and see the screen shots below.