Are you on a limited mobile data plan and do not want to go over that limit?, then with Android 4.0 ICS you can set and control the Data usage directly from settings, it has a nifty monitoring feature that should save you big bucks if used properly. The in-built data usage page also shows you colorful graphs for mobile and Wi-Fi data usage along with details of amount of data being used by apps.
Monitor and Control Data Usage on Android 4.0 without third party apps
You can set your Android phone to disable data usage when certain limit is used or you can also set it up so that it warns you when certain data limit is used within the specified Data usage cycle.
To Set Data usage limits go to
SETTINGS –> DTA USAGE –> SET MOBILE DATA LIMIT.