Pinch it as much as you like. Not sure how exactly you do pinch it, not used Google Docs much yet, so will let you work that one out.
If you created something similar in say OpenOffice, you could have all 31 days going across the page. GoogleDocs seems to limit me to having I think 20 columns - though as I'm not that used to using it yet, maybe there is a way of adding more columns.
You could have a separate sheet for each month, or you could duplicate the cells down the page, removing unnecessary days as required.