f8lure is a free (donation based) ping monitoring service, sometimes called CQM (Constant Quality Monitoring), that can graph the quality of connections.
It works by sending ICMP ping packets to the monitored IP every second and recording the time it takes to reply and if any replies are lost. A graph (see above example) is then created so you can visualise the quality of the connection.
f8lure hs been running since mid-2007 after a similar service called l8nc closed down leaving people stuck. Since we launched many similar services have also cropped up such as pingdom and ThinkBroadband's ping monitoring service. I hope we are better than the other services as we support dynamic IP addresses (dyndns, no-ip etc.), IPv6 and e-mail notifications of connection failure.
In 2013 AAISP kindly setup a FireBrick as a second opinion graph from within their network!