That's a tricky one. You could use an OnTimerScript Script step in a script to run when the record is open for editing (if you have to enter a layout to do this, even better). This would commit the record at a certain interval. The problem then becomes, how long, and then what?
How long do you want to wait? Do you want the record commited without validation, or reverted? Do you want to pop up a window, give the user a certain amount of time then commit/revert record? Do you want to let them know it happened when they get back?
Server also has a disconnect when idle, which I would recommend using, as Steve stated above I would also use an OnTimerScript trigger that commits records at a set time.