Call Meter 3G - Call Meter 3G is an app that acts as a monitoring tool for all your calls, messages, and internet data.
Astra for iOS - Mission control for your money
Data Usage - Data Usage Monitor | Your guard against data plan overages.
Penny - Penny is a personal finance app that takes the pain out of keeping track of your finances.
DataMan – Data Usage Widget - DataMan – Data Usage Widget is an application that enables its user to know how much data he has spent from the total internet package he is using.
Entaxy - Insight into your finances, without sacrificing your data