I've got a Crumpler messenger bag with photo insert. Works quite well, and is a good messenger bag (I'd use it on a bike if it wern't full of equipment, it's got all the right straps).
I think it's the Complete Seed and insert/bucket/whatever they call them.
Don't know if it'll fit exactly what you want, but it will fit a M645 + winder (bigger than a 645AF IIRC) w/ an 80/2.8 and 150/4, two flashes, ~20 rolls in boxes, and a box of P sized filters. And still some room for notebooks/magazines, etc flat stuff. Never had any 35mm stuff in it though.