A good conversation on SproutCore Web Apps - http://www.sproutcore.com/2008/06/30/web-apps-vs-web-sites/ talks about making sure we differentiate between Web Apps and Web Sites.
We need to discover the language to describe our applications so we have a basis of comparison. For example, certain frameworks (like ExtJS) is excellent for Web Apps, but is it good for a Web Site? Having some good terms will help us search for reviews.
Some of my favorite web apps: