Several battery-related jailbreak tweaks for your iPhone/iPad have been recently released and are worthy of mention. BatterySafe will help you avoid draining your battery to the point of shutdown, while Alkaline and NCBattery are cosmetic tweaks for your battery icon.
Anybody who uses Wi-Fi or Bluetooth connectivity on a daily basis has no doubt been frustrated at one point or another when they went to use their iPhone or iPad only to find its battery dead because they forgot to turn off those services. This
situation can be avoided, or at least pushed back a bit, with the new jailbreak tweak BatterySafe. You can download BatterySafe for free from Cydia's BigBoss repository. Once installed, go to Settings -> BatterySafe to configure the settings. Here you can set a battery percentage (10%, 20% ...) that, once reached, will set BatterySafe into action. You can have it turn off Bluetooth, Wi-Fi and cellular data individually or all, if you want. BatterySafe will also dim the device's screen when the danger level is reached, and you can set the brightness that it will dim to.
Alkaline is a cosmetic tweak that you can download from Cydia's ModMyi repo for free. This tweak lets you change the appearance of the battery icon. There are currently only two options, but you can add your own and we can probably expect more to follow. The options are "Bolus" and "Habesha" (pictured above from top to bottom are normal, Bolus, Habesha). Alkaline is a standalone theming platform for the iOS battery icon and doesn't require WinterBoard. You will need to re-spring after changing options.