For a long while I've been using a daypack as my laptop case to stay incognito while traveling. This CompuDaypack from Lowepro goes triple duty with three compartments, adding on a bottom section for a digital SLR camera with the extras.
The back section holds a laptop (up to a 17-inch screen) and a middle compartment holds personal accessories and cables. It has all kinds of pockets, including ones meant for CDs, pens, and business cards. There's a front pocket meant for an MP3 player: you thread the earbud wire through the headphone port and listen to your tunes with the backpack on.
Of course this is more for hobbyist photographers than pros making a living at it. The lower compartment is meant for a digital SLR with lens attached, but up to a 105mm f/2.8, plus 2-3 other lenses or flash units. Naturally there's lots of padding to keep your gear snug and protected.
One thing I especially like about this bag is the handle at the top. More times than I can count, I end up carrying mine that way because I have something else slung over my shoulder, so it's a nice touch. At around a hundred bucks, this is certainly not a bottom-level pack. The back of it is cushioned and although it's really lightweight, this Lowepro daypack feels really rugged and well-made.
The photos here are the burnt orange and black model, but it also comes in black with green or slate gray. Find it at your local photo store or online here:
Get the Lowepro CompuDaypack at Amazon.
Get the CompuDayPack at eBags.