I have quite liked my TAMRAC rucksack, the section at the top is not very
big but you can fit a few bits and pieces in it.  There is also what it
calls a laptop section but I use for maps, books etc.

My only criticism is that it would be good to have a few straps for
fastening things on the outside.  There are two small open elasticated
pockets at the side that can be for water bottles etc but also can take a
monopod (perhaps even a small tripod) you have to improvise some way of
holding it in place.  There are some loops underneath were a tripod can be
strapped.

MB