I think what would be interesting is not in bringing the web to Emacs but rather Emacs to the web; a web browser that exposed everything right down to the rendering primitives in a decent (well, better than elisp or Javascript) language, allowing users to customize how they interact with the web in the way that Emacs users customize how they interact with text.
I guess XUL is the stumbling block for me there. And of course, the browser itself can be modified, for which yay! but really I'm looking for a small set of primitives exposed in a high-level language that can be combined to create web browsers specific to certain tasks; perhaps something like this could be retrofitted onto Firefox, in the way that Emacs was an macro-extension of an existing editor.
