Battery Indicator is a lightweight application that shows the battery charge percentage in the notification area. It also estimates the time it'll take the battery to be empty when not charging, or full when it is.
Additionally, graphical information is available showing level, temperature and voltage for the past 48h.
1.08: Fixed battery time left estimate on some phones.
1.07: Fixed large notification icon for Android 4.0+.
1.05: New, simpler design and more intelligible notification icon for Android 4.0+.
1.04: Added graphical information for the last 48h.