incrediBILL - 6:31 am on Mar 17, 2011 (gmt 0)
It seems that the business model of these services is flawed. I do not see how they can do what they claim for their fees and be profitable. They claim they have servers around the world to monitor their thousands of website customers.
You need to learn a bit more about the technology before jumping to such conclusions.
I use SiteUpTime, have for years, it's deadly accurate, have almost instant notification when my sites or servers go down within 5 minutes of the incident and have never gotten a false positive.
FYI, their free account doesn't even offer PING, it only offers HTTP requests.
Servers around the world is no big deal either, I can get a set of peered dedicating hosting servers for $99/ea. (or sometimes less!) in multiple data centers. You really only need a couple of high end servers to do the bulk of your testing and contact the other servers to validate a failure to make sure it's showing as failed on multiple networks and backbones. Pretty trivial stuff really.