Requirements: Android:1.5 and up
Price: $2.99
Overview: 3G Watchdog Pro.
Guarding you against costly internet overages.
Pro version of 3G Watchdog mobile data counter / monitoring app, featuring:

* Advanced data usage prediction
* Billing rules (counts in blocks, ignores uploads)
* Usage history with graph & CSV export
* Usage by application (Android 2.2+, unavailable on Dell Streak)
* 5 widget styles

* Backup/restore
* Redesigned UI
* Account/SIM with auto switch (requires a phone with a SIM)
* Import settings & data from 3GW free (don't uninstall 3GW free before importing!)
* ... and more!