On 30boxes.com they show 4 weeks at a time (possibly spanning two months) and as you navigate the view shifts by one week at a time. Is there a way to make gmail show 4 weeks at a time and still allow me to move by one week intervals?
I don't think so, however, you could go into settings and use the custom view to see if any of them are suitable. For example, you can choose to show 2, 3 or 4 weeks instead of a month. Keep an eye on their 'Labs' tab in settings as they put experimental features in there (such as year-view).