Web services business models

I liked Webjillion's Will Your New, Favorite Web Application Last?, straight to the point.

Web services is all about building value on top of services you do not (usually) own or control. Does this make sense? Is there a (development/business) model that could make such services more viable?

It looks like more and more people are ready to pay for services provided through the Internet -something a couple of years ago sounded like a blasphemy.