The Saxon XSLT and XQuery processor, developed by Saxonica
eXist-db is a feature rich Open Source native XML database
CAM XML Editor for XML+JSON+Hibernate+SQL Open-XDX sponsored by Oracle
Built for enterprise level and highly customized websites
Information Manager(split/analyze/compare/combine).
xslet project provides some XSL libraries and applets.
Tool for parsing, verifying, browsing and converting EDIFACT and X12
Lemansys LEWS Alternative Framework for Java Web Applications
html5media is a DITA-OT plugin and authoring UI for media insertion