Thanks for the suggestions, I've also discovered some interesting techniques, like the one here: www.bitfolge.de/pseudocron
used in this mod: http://www.phpbb.com/styles/forum/viewt ... 3a6a65e9e3
. This looks like a possible solution, but probably cut down a bit to be more simplified. The one thing that automation potentially adds is lag to page loads, so it's tricky. I don't want to add a huge amount of overhead, especially with a board that is heavily visited. Of course any automation that I added would be optional and set by the admin to true/false in the control panel, so it could be disabled if found to be a burden on the server. I will probably also see about making the cron selectable such that it can be flagged to only initiate on a mod/admin visit to the site, or to a regular user visit.
So I'll look at both the tie-in to user log in, and the img src version for just a regular page view.