Here is one home brew app we can get behind any day. Many people have been asking for an accurate battery meter instead of simply the blocks, and Microsoft responded by providing one hidden away in the settings page.
Now Singularity0821 on XDA-Developers have released his own app which provides an accurate measure of your battery life in a live tile, updated every 30 min. The app also provides logging for those trying to keep track of their charging habits.
Unfortunately due to the hackery involved the app will never appear in Marketplace, but it is currently downloadable to unlocked devices and available in Czech, English, French, German, Greek, Italian, Korean, Polish, Portuguese.
If you have an unlocked device, read more at XDA-Developers here.
Thanks RyoTGZ for the tip.