Muddler Minnow, sizes 8-14. It's been around since 1937, but Don Gapen's Muddler is still popular for good reason. In larger sizes, Muddlers imitate sculpins and darters; in smaller sizes, they can be fished as nymphs; greased and fished dry, they make passable grasshopper imitations.
Woolly Bugger, sizes 6-10. The Bugger is every bit as versatile as the Muddler. White Buggers make fine baitfish imitations. Black Buggers mimic leeches and hellgrammites. Brown Buggers resemble crayfish. Buggers can be dead-drifted, swung across currents, or fished with a strip retrieve. They always catch fish.
Mickey Finn, sizes 6-10. For those times when nothing conventional seems to work, it's time to slip the trout a Mickey Finn. There's something about this streamer's yellow-and-red bucktail wing that turns on reluctant fish. Call it attraction, call it magic, but by all means call it effective.