XED

XED is a text editor for XML document instances. It is designed to support hand-authoring of small-to-medium-sized XML documents, and is optimized for keyboard input. It works very hard to ensure that you cannot produce a badly-formed document. Although it does not validate, the results of offline validation can be accessed, and it does read DTDs and keep track of your document structure, and provides context-based accelerators to make element and attribute entry fast and easy.