New Relic offers SaaS Application Performance Management and Real User Monitoring for Cloud and Data Center deployed web applications implemented in Ruby, Java, .NET or PHP.
Do you like pretty videos? I do.
http://www.youtube.com/watch?v=EOVvl5Z2yHA (Damn you Coderwall for not allowing iframes!)
Note from Coderwall team: we've made up our own list of application performance monitoring tools.