What about a furnace that if you put fuel in it, It will emit a redstone signal till the fuel is burned up. It will have a time meter on the texture and in the gui. The gui will have 5 slots for fuel.
It would be a great idea for map makers, But for survival mode, It would be a good idea for secret doors.
I know we have the bud switch, but with the redstone furnace you just need 1 block instead of 2 (The first block is fuel, The second is the block you need to smelt or cook).
It should be crafted like so: