OK, I'm going to commit this idea to blog, maybe someone can point me in the right directions with it... The timing is semi-due to an article on the BBC regarding accessible website awards.
Having played with Betsie a bit recently, as well as CSS, what I figure would be really cool is to have an "accessibility translator". In its basic form, this would do a Betsie - i.e. take a (non-accessible) website, strip out the HTML and make it viewable to those that need it.
However, it could go further than this by allowing users to attach stylesheets to sites/pages, and letting other people use their style. This effectively allows anyone to skin a basic version of another site. The primary use would be accessibility, but there's not reason, once you have this, why it couldn't be used to redesign any site in any way you liked.
The hard part, I figure, is marking up the cut-down version of a page into something that makes the CSS application easy to do, i.e. group things into divs and spans, et al. It's possible that, given an extremely basic version of this, users of the service could actually provide their own basic HTML-to-CSS-friendly code, submitting what could almost be XSL to the service, although I doubt it need be that complicated.
A server would need to keep a track of the mapping between sites, stylesheets and user-submitted translations, and could do some user-management stuff tied in with it.
So.. who's with me?? :)