crunchbase has a nice list of competitors: http://www.crunchbase.com/company/pingdom http://www.crunchbase.com/company/pingdom Watchmouse appears to have some p

crunchbase has a nice list of competitors: http://www.crunchbase.com/company/pingdom http://www.crunchbase.com/company/pingdom Watchmouse appears to have some pretty high end customers. (including twitter, AT&T and verisign )