3G Watchdog (632 KB), set a quota for yourself and monitor your mobile Internet (3G, Edge or GPRS) data usage, with a status icon shown in the notification bar and a detailed report on your data usage for various durations of time.NetCounter (214 KB), a great tool to keep track of your data usage over cellular and WiFi internet connections for the current day, week or month. Various options are available such as adding or removing a counter, setting duration and data alert.