If you use Notepad as one of your primary text editors, a trick you might not know about is configuring a text file in Notepad to log the date and time of changes. The previous link explains exactly how to do, and as you can see, it is very easy.

While I find this to be a neat function, I personally have several other text editors I use in conjunction with Notepad. Unfortunately this trick only works if you do your editing in Notepad.