Processing XML Data

I’m always looking for some software that will let me process XML data (or any data for that matter) using a tree of processes that may produce multiple outputs from a single input and that may use the by-products of intermediate steps in later steps. With software that has that ability and that also allows me to create new processes that can be inserted into the tree, I can do pretty much anything I want with data.
Here’s some of the projects I’ve been collecting pointers to in hopes that one of them would head in what I consider the “right” directions. So far none of the top three has appealed to me much but there’s a new one called Transmorpher in town that I’m looking at now. A brief glance at the white paper describing it makes it look more appealing than what I’ve looked at before so keep your fingers crossed and maybe we’ll have something really useful for data processing tasks of all kinds.