Nokia have made the new "Counters App" available to download for its Nokia Lumia smartphones, although it's currently only available in beta form.
The Counters Application enables Lumia smartphone owners to track their call usage, texts sent and the amount of data they've used. This is very similar to the Data Sense feature which will be available in Windows Phone 8, which none of the current Lumia smartphones will be able to upgrade to.
Data monitoring has become a pretty standard feature of the current crop of smartphones and it's needed because going over your data allowance can incur huge mobile bills. This new feature should ensure that Lumia smartphone owners don't go over their monthly allowances.
One thing that should be noted is that as Nokia Counters is currently in beta it's not without its problems. Sadly, conference calls don't monitor the amount of data used correctly, while you can only currently set your data allowance in whole GBs.