I concur that the systems mentioned above are good starting points. I will be launching a SaaS and cloud app review and comparison service early 2012. Point is to provide a quality overview of what’s available…
Hopefully this will be of value for you and others.
If others have more references to systems they consider relevant please update this thread and I’ll make sure we’ll look into in with our reviews.
I might add that Page.ly basically is a hosted Wordpress service that integrates with a limited no of themes and plugins (to enable upgrades without issues). Just for info.