Ok, so this may by for the nerdier, as I haven't made an easy-to-use/Windows version; yet! I wrote a simple little Python script that will print out your currently monthly usage, and optionally send yourself an email. I run this as a cron job to send myself an email every day.
I was inspired to do this when my girlfriend installed uTorrent on her new computer, forgot to tune down the upload settings, and saturated my 10Mbps upload for 30 days (ended up costing $60 in overage charges with ElectronicBox this July, apparently there is no cap on how much you can go over
Anywho, the source can be found here: »github.com/quickdry21/videotron
All it requires are the beautifulsoup4 and requests Python libraries.
If a single soul uses this, let me know!