If you want to know when your network is having issues and have some Arduino gear kicking around this Uptime Monitor Project by www.hackshed.co.uk allows you to get instant Twitter updates as soon as there are problems.
Thanks to Steve for sending this in.
“It was actually surprisingly easy; we had the Twitter posting code from the previous project and we found an Arduino ICMP library so that we could test a ping to the hosts and see if it was responding or not, we added this to our task scheduling code and the rest just fell into place.”