Greg left a note mentioning the free monitoring service, Monastic. It doesn't have as much functionality as SiteUpTime.com, but you can monitor 100 sites. If all you are doing is trying to track when your site(s) are down then it seems like this might be a better solution than SiteUpTime. So, as an experiment I have both monitoring systems monitoring the Tech Soup in Second Life site. If I have any revelations, I'll share.
Written by: Creech