Opera Mobile the popular web browser for mobile platforms, has released an updated version for Android which allows you to find the data usage. Opera Mobile 11.5 will now show you exactly how much data you have spent and saved using the product and, in turn, the money and time you save.
You can access the data usage page from the help menu inside the Opera Mini and Opera Mobile browsers, keeps count of how much data you are spending and saving in total, or for a specific timeframe like a trip abroad with roaming.
It shows you the MB saved while Opera Mobile browsers can directly translate into money saved if you are roaming or on a pay-as-you-go plan for data traffic.
More details available here. You can download Opera Mobile from the Android market.