Here's a simple calendar widget. It would be easy to extend this with
functionality to keep track of appointments, etc., once applets have a
persistent space of their own.
The single arrow buttons (<, >) advance by one month; the double
arrow buttons (<<, >>) advance by one year.
To return to today's date, click on the month/year label at the
Caveat: dates outside the reach of the Unix time function (1970-2037)
cannot be represented.
Here's the source. (The clock widget at the
bottom comes from the clock widget demo.)