I bet a lot of folks could use this app to alert them when they are getting close to their limit on minute plan. I would add that some carriers only update this data once a day or less, so set an alarm earlier than you think to be safe!
A Day in the Life of a Presson…
Co-discover Interesting things :)
A Day in the Life of a Presson... 
I beleive it pulls the minutes for the account; try it and let me know!
Since we have a number of phones on a shared plan, I wonder if it can add them up and give a warning based on the total?