I spent this morning further hacking on the axkit.org mailing list archive software (which I'm also using on the Photogeeks list archive).
The first component of this is an XML generator for ezmlm-idx indexes. It uses SAX, and it was kinda nice to get into XML a bit again, although I don't want to spend too long there
After the index generator I have a whole bunch of XSLT files to re-thread the mailing list. This is quite nice, because XSLT is natively tree-based. The only complex bit comes when displaying orphaned threads in the month-view, but thanks to the guys on #axkit-dahut and Michael Kay's XSLT book I soon sorted that out.
All in all I think it looks fairly good. And a hell of a lot better than ezmlm-cgi.
Feel free to take it for a spin: http://axkit.org/archive/.