Between Flash/Silverlight and native is Java. With Java7, you get GPU accelerated multimedia, "applets" not restricted to the browser, point & click deployment with Upstart ..

Very few people are doing client-side java these days, but those are making some rich, immersive experiences, across platforms, and with push deployment.

Having said that, client-side java is hard; No "authoring" tools, all UI & visualization is made by programmers .. not exactly the most discerning of aesthetes ;-)