SPRINGHEELMAC I agree, that would be a nice feature. However, if you are concerned about your computer being idle, consider 'Boinc' or 'Folding@Home' (both available here). Both programs participate in "distributed computing" for good causes; basically, your computer processes data for research in various fields in the background during idle time (or continuously,if you so desire, that's what I do). Its a good way to avoid feeling guilty about leaving the computer running if you must.
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