Tested on:
- HTC P3600 (WM5) [working].
- Mio 168 Digiwalker (Pocket PC 2003) [working].

Update Description:
v1.1 (19-01-2009):
- Customizable bar.
- More information about battery.
- Some bug fixes.

v1.0 (06-08-2008] :
- Initial version.

SOURCE

http://www.flytrap.it/default.asp?p=wmminibattery#eng

Reviews:

**** [Jun 2, 2009] by Stadt using HP iPAQ hw6915 (Windows Mobile 5)
Nice program, thanks

**** [Aug 9, 2008] by Hayden using Cingular 8125
It works like a charm. I love it. My only suggestion is that I wish you could change the color of it. Or maybe just use the base hue. Otherwise, I like it.