This is a simple uptime report for BTP, which utilizes an uptime monitor at: http://uptime.openacs.org/uptime/about.adp The actual uptime monitor, which justs lists up, down, up, down etc. is here
It's not amazingly accurate, as most downtime only lasts a few minutes (at least on this host) and the uptime monitor thing only runs by every 10-15 minutes or so, but it's something that's easier to understand :) Also it only measures server uptime. Not when MySQL etc. is down