Billingham started as a company that made fishing bags, then adapted them for photographers. They are quite expensive, but seem to have set the standard for quality, of which I can't comment.
Originally Posted by Cold
I use a Domke F6 in olive drab. When I worked blue collar it was perfect for one 35mm camera with lens and motor drive attached, one spare lens, and my lunch! It's held up pretty well, considering I used to have to cross train tracks, jump a fence, and walk across a golf course to get to work from the parking lot. The bag has plenty of padding on the bottom, but hardly any on the sides or top. The canvas is treated for water resistance that protected my camera through several Utah winters.