Newbie system admin

I'm setting up a site where we want some threads/some forums to be populated semi-automatically (e.g. by running a script) according to information held somewhere else (e.g. our association's membership records which are held in another database). This repopulation doesn'y need to happen everytime a user refers to the thread - it's sufficient for the system manager to "flip a switch" and reload it when he knows that the external database has been updated.

Has anyone written a hack to do something similar?