My Nikon bag would weigh half what it does if I took the stuff I rarely need out of it. Let's see, a flash light, a red bulbed flash light, a pen, a pencil, a pad of paper, Kodak's mini Photo Guide (the one wwith all the wheel calculators) a folding scrim, an 18% gray card, a mini-multi tool, a color halo filter, a half close-up filter, red filter, a clear filter, an electrical shutter release cable, a packet of model release forms, a packet of business cards, tooth picks, tape, several of those little black triangular paper clippy things, a table-top tripod, step-up and step down rings, a yellow blue and green filters, neutral density filter, polarizing filter (all in a removable filter wallet), reversing ring, a flash extension cord, lens hoods I never put on, a regular cable release. Somehow I also fit in the main stuff: a digital body (d2x), film body (f5), backup film body (n80), some lenses (20, 50, 60, 85, 180 and 12-24) and a flash unit. Oh, and the manuals for everything that has one.
The bag weighs a ton. A metric ton at that.