AutoWifiSwitch

Use WiFi extenders? Tired of constantly finding yourself connected to the wrong network? Look no further, AutoWifiSwitch will automatically connect you to the best network in range that has previously been connected to. This is done by periodically scanning for networks and determining if an attempt to connect should be made.

The app is highly customizable, featuring a "Difference Required" option which will only connect to a better network if it is x amount better than your current connection. This solves issues whereby in certain areas, the app will constantly switch between 2 networks. The app can also be setup to use different scanning intervals when asleep (locked) to save on battery life.

The app currently only requires 4 permissions:
ACCESS_WIFI_STATE - Allows the app to check if you have WiFi enabled
CHANGE_WIFI_STATE - Allows the app to scan for WiFi networks
RECEIVE_BOOT_COMPLETED - Allows the app to start on device power up
QUICKBOOT_POWERON - Same as above, except for HTC devices