http://liquidninja.com/metapad/
They have metapad and Full and LE. No install is needed either but make a folder to unzip it too so you keep the files in one place.
But FAQ says this.
[7] - .LOG files
Q: Is the feature of creating a log file that appends the date and time, a capability in the original Windows Notepad, still available?
A: Yes. Here's How you do it:
1. On the first line of the text file, type the following at the left margin: ".LOG" (in capitals, and without the quotes)
2. Save the document.
Note: Every time you open this document, metapad will append the current time and date, as specified by your computer's clock in the short date format (see previous question), to the end of it.
It works in notepad too. You do not have to name the file log or anything. Just open the file up and and at the very top type
.LOG and each time you open the file you will see the date and time like this here
12:25 AM 3/1/05 If you open it and do not type anything it will still ask if you want to save so say yes if you want the new date added or no if you was only wanting to read it and no add the date to it again
So try it with note pad. Also the free metapad is nice so check it out.
I just did it and open and closed it and save the file each time and it looks like this.
.LOG
12:18 AM 3/1/05
12:19 AM 3/1/05
12:19 AM 3/1/05
12:25 AM 3/1/05
12:32 AM 3/1/05
I could of typed what ever each time but I would alway have the date and time I opened the file now.