Please note that the issue about WiFi not working on device unlocked reported by users in the comment below has already been fixed.
★ PowerGuard Pro Version - take more control and options in extending your battery life. PowerGuard Pro defends the battery power from power hungry parts of your Android device - which are WiFi and 2G/3G data connections. PowerGuard Pro regulates these WiFi and/or 2G/3G connections based on your need and configuration. Extend your battery life to lasts almost twice the amount of time than without it - given the same usage behaviour.
PowerGuard Pro will always try to connect through WiFi and 2G/3G first. If it is unable to make a connection through WiFi within 15 seconds, then it will disable WiFi to conserve more battery power.
Try the free version.
★ Widget to enable or disable PowerGuard*
★ Widget to enable or disable Emergency connection to internet.*
★ Widget that displays battery level and temperature.*
★ Choose connection method whether to use WiFi only, 2G/3G only or both.
★ Turn on Wi-Fi/3G only when specific application is opened.
★ Option for Power Guard to ask subtly (using notification bar) if you need WiFi/3G when an application is opened.
★ Turn on Wi-Fi/3G when device is unlocked. This only works if application monitoring is off.
★ Turn off Wi-Fi/3G when display goes off.
★ Schedule when Wi-Fi/3G should turn on or off every day.
★ Make periodic Wi-Fi/3G connection at specific duration when device is locked giving the device more time to enter into sleep mode but still give a chance for your emails to synchronize.
★ Hit Emergency Connect to enable Wi-Fi/3G connection for 30mins (configurable) then turns off WiFi/3G automatically.
★ Disable Power Guard when certain battery power level is reached.
★ Shows battery level and temperature in notification area.*
★ Shows WiFi and 2G/3G connectivity status in notification area.*
★ More configuration option, like changing temperature unit.*
*Note: Available in Pro version only