Rinzo is a free open source Eclipse plugin that provides pure and java integrated xml documents edition. It's widely used for its performance on big xml documents, syntax coloring, XPath evaluation, DTD/Schema generation from xml, java class names proposition and since version 1.3.0 from its jaxb classes and parser generation.
Wants more? Rinzo improves edition with these useful features:
Take a look at the features section for more details of what you can do with Rinzo.