Rich Internet applications (RIAs) attract site owners' attention because users like them, they enable interactions that HTML can't, and they get results. Yet many site owners considering RIAs wonder if they're worth the investment even as many who already employ RIAs struggle to assess their true value. Our research and conservative models show that well-designed RIAs can produce eye-popping results that can help prove the value of current investments and make the case for future RIA projects.