AFWall+ (Android Firewall +) is a firewall for Android which allows you to limit access to Wi-Fi or 3G for certain apps that you specify, like apps that are traditionally heavy on your bandwidth.
AFWall+ (Android Firewall +) has two modes: using a whitelist or a blacklist. With the first, you choose the apps that can access the network; the second is reserved for those you wish to block.
AFWall+ (Android Firewall +) is activated manually or via a widget. It only works with root permissions and includes a log for tracking firewall activities.