If you have a broadband internet service with a monthly download limit, you may find SurplusMeter comes in handy. It measures the download and upload traffic on your Internet connection and keeps a record of your traffic volume. It gives you all kinds of useful output statistics, like daily allowance, average daily usage, accumulated surplus, and more.

Statistics are presented in three ways: simple bytes in/out; summaries of megabytes used and remaining, and graphic meters which display at a glance when you're getting close to exceeding your limit.