I know it doesn't directly link to the suggestion, but there is a web based calculator:
http://grodanboll.se/tsoc/
The suggestion of having buildings automatically sleep when unbuffed has been suggested a few times (similar to this)
Another suggestion could be to have an option where when placing supplies on a resource you can pick either the quantity of the resource or how long you want it to last (so the amount is picked automatically based on the buildings level/amount of buildings/travel time).
But in general I would agree there could do with something being done regarding the mines running dry/stuff running unbuffed without having to set a bunch of alarms outside the game.