I use http://wasitup.com http://wasitup.com and the free version of http://pingdom.com http://pingdom.com. Both seem to work well, although Pingdom has the adva

I use http://wasitup.com http://wasitup.com and the free version of http://pingdom.com http://pingdom.com. Both seem to work well, although Pingdom has the advantage of a monthly summary.