Thinkbroadband site have a useful little tool to monitor the quality of your internet connection. It is designed to work with a static ip, but can be set up with a dynamic, the only problem is creating a new one after every disconnect (if you are unlucky enough to get regular disconnects).
Would be good to see how it works on users lines, so create one here ( http://www.thinkbroadband.com/ping/monitors.html ) and it would be handy if results could be posted here so we can all see what is happening nationwide (hopefully)
Mark