We have a wood stove with a glass door. Tried newspaper, ash, and the cleaner jdunham recommended. The cleaner works good but requires a lot of work.
This is the best stuff we have used:
MEECOS-RED-DEVIL-701
Just search on Amazon.
It says on Amazon that the product is not for use on gas stove glass. I ordered the Rutland to see if it does a better job than the Simple Green.