Joachim Zobel has created an awesome Apache 2.2 module called mod_sqil. I haven't built or used it yet but it does something quite similar to the query handler in Nexista - it takes an XML based query, prepares it (inserts parameter values), and then formats the result set into an XML document. Actually its not mod_sqil that does that directly, but with the help of some other modules, that can be achieved. http://www.heute-morgen.de/modules/mod_sqil/
Since you like mod_sqil, you may also like Cindy:
http://search.cpan.org/~jzobel/Cindy/
Thats thought as the upper half of the noapp stack. It does content injection. A syntax remotely resembling css is used to move content into an html document.
Hi Joachim, Cindy looks interesting, but I'm all about XSLT.