I have had alot of success with the following:
Cone/bead head egg sucking leach - Especially with a spinner blade in front of the cone or bead.
Egg patterns: of course.
Crawfish patterns - Especially good for the steelhead and browns but works often for the salmon as well. I have watched fish chase this fly across the run striking at it multiple times when they miss it. I have also caught a fish on it, cast again near the same fish after releasing, and had same fish chase it again. They sometimes won't touch it but other times will want to kill it more than anything.
Large minnow patterns - Use patterns that resemble shad and smelt and tie them like you would for largemouth bass. A salmon/steelhead/lake brown is not a little fish and will have no trouble hitting even a four or more inch fly.
Clouser minnow.
Just about anything...

Once, I saw a bass sitting in a hole not far from some Salmon. It was large, probably approaching 6 pounds, so I decided to give him a cast with a topwater just to see what would happen. I tied on a popper and cast upstream of him. Gave it one pop and a salmon moved out of it's hole, looked at the popper as it was floating downstream, I gave it another pop, and the salmon exploded on it. I caught three more salmon on that popper that day and never got another hit from salmon on any fishing trip after that.