Do you have a monthly, weekly or even daily data limit on your mobile account? I know I do, which is why we leapt at the appearance of Data Monitor as a utility to help keep track of usage. However, with barely more data-gathering functionality than the built-in Log utility and with an intrusive and hard-to-configure, always-on 'ticker', it seems that Data Monitor isn't ready for the prime time just yet, as you can read in David Gilson's review.
"The term "unlimited data" is an infamous fallacy in the mobile industry. However generous, there are always limits, and so each individual has to keep track of how much data they have consumed. This is just what DataMonitor by One View Systems is meant to help you do."