I use org mode to keep track of my daily projects . . what I'm working on,
etc.  I tag work related items, and, when I export to html, only work items
are exported.

What I'd like to do, however, is only export things that have changed, or
have been dated in the last week.

Similarly, I'd like to archive off old completed tasks.

Could someone point me to how to do these things . . . I'm sure it's
documented somewhere :)

-Dave