Now as open source: http://www.github.com/mudderman/battstatt

A simple home screen widget that displays the current battery charge in a literal way instead of a meter. A small text will also be displayed if the phone is charging. 4 Sizes are available: 4x1, 2x1, 1x1 and 1x1 with numbers.

Motorola Users:
Motorola devices (at least the Milestone) only reports its level every 10%, so it can't get more accurate for you than that I'm afraid.

Recent changes:
Now as open source: http://www.github.com/mudderman/battstatt