This [[Emacs|http://www.gnu.org/software/emacs/]] function from Michael Fogleman simplifies editing tiddlers in `*.tid` files by automatically updating the `modified` field.
If you have Emacs, you can save this function somewhere (such as in your init file). When you finish editing a tiddler, you can call the function, and it will update the modified time.
> Help Wanted: Even better would be a TiddlyWiki-mode that used this function as a save-hook