[wa-fu]

I use Invisible Glass by Stoner.
I also use something called Bar Keepers Friend on the outside of the windows if they are really dirty.  I found it at a bed and bath store.  I heard about it on a car show.  It is a powder made to clean & polish glass, metal, countertops, etc.  I just put a little on a wet sponge and gently scrub the wet windows and then wash it off.