When there is need for a fast and powerful editor I really like Notepad++ . But it bugged me a bit that there isn’t a function for formatting XML.
Recently I stumbled over the plugin “XML Tools”  which added the desired functionality. Like!
Two small drawbacks:
- the default shortcut for formatting is set to CTRL+ALT+SHIFT+B … seriously ?? Anyone out there who can use that shortcut without a cramp in his fingers ?? Fortunately you can simply change that in the shortcut-dialog…
- the plugin formats if and only if the XML is syntactical correct
-  http://notepad-plus-plus.org
-  http://sourceforge.net/projects/npp-plugins/files/
Works great! Very useful when you want to check tab errors. Thanks