What is a good non-toxic glass cleaner?

Dunno if it's non-toxic... but Method has great bio-degradable cleaners; You can get them at Target.

Make your own: 1/4-1/2 teaspoon liquid detergent; 3 T vinegar, 2 cups water, spray bottle. Mix and shake. Soap will remove residue from commercial cleaner built-up. Use a professional squeegee and on cloudy day. For more green do-it-yrself products, http://www.care2.com/greenliving/make-your-own-non-toxic-cleaning-kit.html

*For windows.

soap and water and lots of scrubbing from a green/yellow dish-washing scrubbing pad always seemed to work well for me ... oh yeah, and lots of arm strength patience for tougher stains :)

ammonia water; melts dirt, evaporates fast. use newspapers not paper towels because the ink attracts the dirt.
don't ask me why this is so; but it works, bizarrely enough. and it's greener than using p. towels.

it's not actually the ink that attracts the dirt ... it's the paper: newspaper is naturally more absorbant of ink (and other stuff) than regular paper, or so says realsimple.com's article on 101 extraordinary uses for ordinary things (there's a section on newspapers) ...

I also need to apologize to occ for suggesting ammonia, which is neither non-toxic
nor unscented. Too excitable about fluthering. Got all flustered.

alternate solutions can also include vinegar and/or lemons ... whose things are acidic, so they should work ... for really tough stains that you want to "score", you can use salt or sugar (the crystaline kind) ... those little things are really hard!