Don't spend money on Windex or other glass cleaners when you can make your own that's just as good or better. Mix some white, distilled vinegar and water, add it to a squirt bottle and go to town. It not only cleans glass but counters also.
Vinegar is also a great cleaner everywhere else because the acidity kills bacteria, mold, and other nasties! Add some baking soda to the mixture and it becomes a great scouring agent for bathrooms.
More cleaning ideas can be found here:
The Naturally Clean Home: 100 Safe and Easy Herbal Formulas for Non-Toxic Cleansers