I used a new type of software for the first time today. It's called Olifant software, and is available via free download. It's pretty nice. It lets you look in a TMX file, and change the data and tags etc. It's a small file and seems not to be as buggy as the bigger versions are.
I personally like to use small files, as they tend not to break down so much, and work a lot quicker. The menus are clear and clean, and because of the limited options its easy to use. I just figured it out right away without reading the manual at all! So if you need to edit TMX files, Olifant is worth a look.
You can read more about it here: okapi.sourceforge.net/Release/Olifant/Help