Matt Kingston modified my Blogger + ASP + XML tutorial to show how it's done with PHP. very cool. This reminds me that I've always intended to write more about XML + Blogger. (eg: how to set up a simple search, how to write out the archive index on any page, or how to enable remote editing.)
Not related to Blogger...a lot of the picture stuff I have on this site is done with writing out XML representations of file structures on the server...then transforming those with XSL. I've been meaning to write some of that stuff up too.