Actually, you could say it's just the opposite. Russ Blessing designed the Wooly Bugger to imitate a hellgrammite -- the nymph of the dobson fly. So, it's really a nymph that many people fish as a streamer.
Some of the flat wing streamers like the Wood Special (like the one at http://globalflyfisher.com/streamers...wing/woods.htm) work very nicely as large stone fly nymphs when dead drifted.
The pattern that I would use to imiate iso nymphs (Prince Nymphs, Zug Bugs, etc) are often better fished like a small streamers, since the naturals are active swimmers, so those sort of straddle the line. And almost anything I'd use to imitate Green Drake or Hex nymphs could be called streamers, just due to the sheer size.