Many ISPs limit the amount of data you can move in a month--but if you don't know how much you've downloaded, how can you avoid getting cut off at a crucial point? BitMeter II is a bandwidth meter that tracks your downloads and uploads and presents the data to you in myriad ways. You can track your data's current download and upload speed, for starters, in a handy graph that lives in a tiny, free-floating window. Once you've got a bit more data moved, you can appreciate the graphs and spreadsheets that chart your data patterns by hour, day, week, and month.
For many users, the killer feature is the ISP Restrictions screen. There, you can tell BitMeter II your ISP's monthly limit and request an alert when you approach it. An included calculator helps you determine how long a download will take. Both of these features will help you budget your online time more efficiently.
I liked the audio notifications for bandwidth use. It alerted me whenever yet another program took it upon itself to automatically update, helping me understand the burden on my system and my broadband at any given moment.