Around here gear fishermen talk about hellgrammites being the best bait for smallies, although they talk about crayfish too. There's a fair amount of smallie water around here, and I love fishing for them. #8-#12 Black, or brown and black wooly buggers or wooly worms do pretty good as an imitation for the hellgrammites, although I have seen actual hellgrammite flies at Slate Run Tackle Shop in PA.
The hellgrammite is the larval form of the Dobsonfly. Check out Troutnut.com for pictures and more information. They're ugly suckers. Wikipedia has info too. I'd post links but I haven't figured out how yet.