If you'd like a master list in which all the files are sorted together by modification date, showing the directory they're in, but not grouped by directory, you can use this:
For those of you using Mac OS X, option -printf is not available on BSD find (you will get this error: find: -printf: unknown primary or operator). Fortunately you can Install GNU find through Homebrew (there should be an option to Fink and Macports as well):
brew install findutils
After install it the GNU find should be available to you as gfind. So, all you need to do is change the line above to: