This is shamelessly wanting to do the same thing as the Adobe pdf reader.

In Adobe's PDF viewer it is really easy to move up and down in a pdf document by
simply rolling the scroll wheel (on mice that have this wheel).

In GUI environments, usually the user has their hand on the mouse, so it makes
sense to not have to get them to move their hand off the mouse to move
forward/backward (going to page up/page down). Getting them to navigate to the
next/prev buttons is better than nothing, but requires a navigation effort,
whereas using the scroll wheel is mindlessly simple.

If compatibility with systems without a scroll wheel is important, perhaps
something like a scroll bar along the side (again like Adobe) or a right mouse
drag might be useful as it requires less thinking than having to navigate to a
particular place on the screen and press it carefully.

Scroll wheels are becoming very common on mice these days, should this be an
issue for you.

Regards
David

PS On another note, how hard is it to have a rolling display of pages rather
than just one discrete page at a time. This would be nice (again, like Adobe's
reader).