Try this simple method using baking soda and a wet soapy towel for a cheap and effective way to clean up your smooth glass stovetop.
Dish Towel that's wet with soapy water
Fill your sink with warm soapy water. Put a clean dish towel in the soapy water and get it thoroughly wet.
Next, sprinkle some baking soda around on your glass stove top. If there are any particularly dirty areas, sprinkle a little bit more baking soda in those spots.
Take your wet dish towel out of the sink and wring it out a little bit (so that's it not really dripping wet).
Lay the wet towel on the stove top, over top of the baking soda that's been sprinkled around.
Let things set like this, with the wet towel on the baking soda, for about 15 minutes.
After the 15 minutes has passed, use the towel to wipe and clean the stove top, scrubbing around the baking soda a bit as you go. You may want to rinse the towel with some fresh water at the end of the scrubbing so you can wipe away any remaining bits of baking soda.
Finish things up by wiping the stove top with a fresh dry towel, or some paper toweling, to wipe away any remaining moisture. If there are any cloudy spots left from the baking soda, I find a few squirts of my vinegar cleaner (made with half water and half white vinegar) works well to clean them away.