OSopinion has an article about 'How Mozilla Could Help Us Take Back the Web' which has nothing more to say than that Mozilla needs a killer feature for the one point oh release. Of course it does! And it already has a killer feature called standards compliance. The latest milestone build (0.9.7) notes the following new features...
The DOM Inspector is a tool that can be used to inspect and edit the live DOM of any web document or XUL application. The DOM hierarchy can be navigated using a two-paned window that allows for a variety of different views on the document and all nodes within. If you're using the Mozilla installer, be sure to switch from typical, to complete or custom install to install the DOM inspector and JS Debugger.
That last bit about the JS Debugger is a killer feature for the web interface developers of the world. But, for the public at large, a killer feature comes in the form of something like Napster which defines a whole new market, which is NOT the mission of Mozilla. The OSopinion author goes on to say "The only way Mozilla will wrest the Web from the iron grip of that overshadowing blue 'E' is by providing its users with a killer feature that has universal appeal." I argue that the universal appeal is compliance with standards as defined by the W3C.
Also, I have yet to see anyone go about creating a 'killer app' and actually succeed on the level of Navigator or Napster. These were accidents like Silly Putty.