I have a monitoring thing setup so that it sends a message to my mobile whenever a server fails to respond. It didn't fire yesterday for some reason otherwise I would have fixed it straight away. If the forums go down in the future (it shouldn't happen often) and they remain down for more than 5 minutes I would appreciate it if someone would send an sms to the number on this page - You must be logged in to see this link. Something simple like "Forums down" would be enough.
You should send one sms only at any time of the day or night. I probably won't respond but at least I will be notified straight away and be able to start fixing the problem.
In the future, when I finish the upgrades I'm doing at the moment I will look into using our backup server to automatically take over (its called a failover system).