Sip that precious juice with Deep Sleep Battery Saver for Android
The app keeps your device in deep sleep mode most of the time when not in use, thus sipping on that battery juice as little as possible.
In this regime most everything is off, including 3G and background apps, so your handset only maintains connection to the most frugal network bands, and wakes up rarely to accept some push notifications, then slumbers back, as you can see in the concept algorithm above, drawn by the developers.
There are 5 profiles to choose from in the basic version - Gentle, Balance, Strong, Aggressive, and Slumberer - with each increasing the time between short wake-ups for push notifications. You can also whitelist apps such as the music player or set a deep sleep block if data traffic is above a predetermined threshold.
In the PRO version, which is $1.29, the user can go into even more granular detail with custom profiles - for example, have different weekday and weekend settings, and set different radio and sync mode switches. Naturally, both versions sport a simple on/off widget, and notification bar presence.
There are much more tweaks and adjustments to play with, depending on what exactly you can make do without when the screen is off, so you can check out this versatile battery preservation app from the source links below, and visit the XDA-Devs thread of the developer for some insider info.
Things that are NOT allowed: