I've been looking for a pingdom replacement for the very same reasons GP mentioned. Webmon does look interesting, even though it does appear a bit more expensive. It seems penny-pinching if you consider the cost of downtime, but despite all my complaints about pingdom, it still works and does its job. So I'd need a compelling reason to switch and it's always easy to convince upstream when the price is cheaper or you get something better.

Just a quick question: what's a 'target'? is it the equivalent of a pingdom 'check'? or is this an endpoint IP that we can run several checks over?

Some feedback after a quick glance on the homepage - it's nice and seems to provide the most important info, but I'd appreciate some more in-depth info on some areas (to answer my question about targets and possibly other questions about other stuff: what's a user, what's a dashboard etc)