Hi LikMeng,
I have also been wanting a date-stamped type of My Notes module that is ongoing.
It seems like we are very close but not quite there yet. For example, as you mentioned, a journal that you can add date-stamped entries to, the dialogue module does date-stamp entries, but is not personal, the new wiki stuff is close but no date-stamp and still in development, and Williams Castillo started developing a "Bookmark" module (see http://moodle.org/mod/forum/discuss.php?d=3125) that a student could enter notes on an ongoing, date-stamped basis, but unfortunately this module has not been perfected.
Maybe somebody soon one of these will work.
Chardelle