XML Marker
XML Marker is an XML Editor that uses a synchronized table-tree-and-text display to show you both the hierarchal and the tabular nature of your XML data. It automatically produces a tabular display of any selected tag by collecting repeating attribute and tag names and then arranging them into... More features include table sorting, syntax-highlighting editor, automatic indentation/pretty-printing of exiting code, drill down and as-you-type syntax checking. ... You can dramatically increase their usefulness by modifying your programs to produce them in XML format.
http://symbolclick.com/xmlmarker_1_1_setup.exe - 997Kb - Download - Screenshot

ECMerge Pro (Linux)
ECMerge compares and merges files and folders, side-by-side or 3-way. It is designed for software engineers, web authors and other professionals who work with multiple revisions of text files or who need to keep multiple folder hierarchies in sync. Two text files or folders can be compared to a... The integrated XML pretty-printing filter allows great comparisons for XML files, the equivalent output filter can compact the XML into one-line file. ... A shell extension is provided under Windows to select items to compare and launch ECMerge.
http://www.elliecomputing.com/soft/ecmerge-1.1.27.linux.x86.tgz - 4Mb - Download - Screenshot

ECMerge Pro (Windows)
ECMerge compares and merges files and folders, side-by-side or 3-way. It is designed for software engineers, web authors and other professionals who work with multiple revisions of text files or who need to keep multiple folder hierarchies in sync. Two text files or folders can be compared to a... The integrated XML pretty-printing filter allows great comparisons for XML files, the equivalent output filter can compact the XML into one-line file. ... A shell extension is provided under Windows to select items to compare and launch ECMerge.
http://www.elliecomputing.com/soft/ecmerge-1.1.27.win32.exe - 3Mb - Download - Screenshot