ASPhere is a freeware utility primarily intended for creating and modifying configuration files for ASP.NET. But they are not only web.config files ASPhere can work with, you can use it for viewing and editing normal XML files and plain text files as well.
It offers you a graphical user interface for editing XML-based files, a text editor with syntax highlighting, intelligent contextual help and other useful features such as comparing files.
graphical interface for editing XML documents
editor with syntax highlighting and contextual help
ability to have several files opened simultaneously
files can be managed in a project
file compare function with highlighting differences