ok, its actually not that hard to build one yourself; if you want a calender for each individual user.
You'd set up the db thusly:
table name: new_date:
fields: username, date, notes
So the code would be simple, the user would have infront of him or her a calender, very simple to build. For example just have a html table for this month, and if they click for next month it will generate the right amount of cells, corresponding to the amount of days in that specific month. It will also select all from the db and place the notes in the cells, or have a link with perhaps with GET information in it, to tell the page the user is re-directed to the correct information to display the correct note for that date.
In each cell you will be given the option to add a note, once clicked the user will be re-directed to a new page and the date that a note is going to be added to will be generated through GET information.
Then its just a matter of inserting it into the db.