The now ubiquitous 16:9 screens are capable of displaying three pages of typical print material (A4 or letter sized pages, technical reports, etc.) side by side.  It would often be useful to make use of all the available space for onscreen reading of such material. 

This could be done in several ways: 

* A "Triple" mode which displays three pages ("fit to visible", see https://bugzilla.gnome.org/show_bug.cgi?id=169676) or better manually positioned for maximal zoom level at which continuous reading is possible), page up/down would only go one physical page up or down so that any three consecutive physical pages could be positioned on-screen for continuous reading.  

* Really cool would be a "horizontal continuous mode" where one could continuously move, with the mouse, a horizontal band of vertically maximized pages, left or right.  (Personally, I think this would be much more useful than the vertical scroll mode ("Continuous") which I almost always switch off because the physical distance between the last relevant line of one page and the first relevant line, excluding footers and headers, of the next page is usually far to big for documents which have been laid out for printing.)