You might have heard that Notepad will fail to display correctly a file holding this single line: "this app can break" (or any sentence built on the same 4/3/3/5 scheme).
This issue could be tracked down to ANSI vs. Unicode text autodetection.
However, there is a much cooler Notepad trick in the latest issue of 2600 magazine. If the first text line happens to be ".LOG", Notepad will automatically append last modification time at the end of the file (as documented in KB81067). This feature is available from Windows 2.03.