I always wondered why "Web apps" have to be made with HTML and accessed through a URL. Web apps are basically regular applications with a shared user database. If you have a graphics intensive application, instead of using AJAX, why not use mature client-side graphics facilities and release a downloadable program that talks to a remote shared database for Web 2.0 style functionality? The only downside is that software updates are harder to propagate, but with update alerts this is not so much of an issue.