One site was hit by Panda 1 and 2. Another was hit by Panda 2 only. I blocked pages that, although useful for visitors, could be considered "thin" for searchers (there were quite a few). Robots.txt at first, it was too slow, so I switched to noindex tag. I also did some major redesign in terms of layout and ad placements. Those sites haven't improved one bit with Google. One nice thing, my redesign at least helped improve Adsense performance somewhat. But at this point, I might as well stop working on them and move to others projects. Years of work down the toilet makes me wonder if I should have gone black hat instead, but I don't think I could look at myself in the mirror. This Panda update has put the fear of Google in me.