Android: Android's default battery icon is pretty small and doesn't give you a good idea of how much battery you have left. ChargeBar puts a thin line at the top of your menu bar, giving you a much more accurate representation of your battery's charge.
ChargeBar is based off MIUI's lock screen battery indicator, which is a handy way to see your battery's charge at a glance. ChargeBar essentially puts a thin line at the top of your screen (or, if you prefer, below the menu bar or at the bottom of the screen), showing you how much battery you have left. You can change its colour, thickness and animations, as well as hide it in full screen apps. It's completely free and well worth using, if you're sick of trying to judge how full Android's tiny battery icon is.
ChargeBar is a free download for Android only.