From Brad McCoy:
McCoy XML Viewer is a simple XMLdatabase viewer that reads the database into a tree view format. The nodes can then be cut and pasted to and from the tree. You can also type a new node into the text area and the parser will grab it and create a tree node. Each node can also have a set of properties associated with it as well. You can add and remove properties as well as edit existing properties. As an extra you can take a file and drop it into a text area and the parser will import the file into the tree.