Shelter - Isolate your Big Brother Apps
Greenify - Greenify is a mobile app that gives you greater control over your Android device's power usage, allowing you to get a lot more mileage out of your battery life without having to constantly plug it back into a charger.
island - a free and opensource alternative to parellel space
Accubattery - Monitor's battery capacity through the use of science
App Cloner - Clone your Android apps so you can use multiple logins.
Power Battery - Power Battery, as the most professional battery saver app, could get up about 60% more battery life for Android phones or tablets.