Public knowledge base interface (repost, sorry)

(sorry for the repost, this got stuck in another thread due to
"in-reply-to" headers)

In our current home-brew ticketing system we make the correspondences of
our previous tickets available to the public through a simple search
interface on our home page. If a customer does not wish their ticket to
be publicly accessible we can mark it as “private” and it will not be
included in the search results.

I am looking to replicate or improve upon this with RT. The
public/private status can be handled by a custom field, but does anyone
have a good idea of how to allow public (non-authenticated) access to
past tickets on a per-queue, searchable basis? The simpler the better.