Interesting thread, thanks. Seems Claarky's had a Road to Damascus experience. Just read monkeysphere article, well worthwhile.
Having just tried noindexing, see if can help a recent slump: it surely can help with exit rates, too.
I've targeted pages for keywords (free tags), which are just lists of articles/photos.
I reckon not so good if these are pages people arrive at via google, so deindexing seems best; but once someone is on site, and wants to find more about one of the keywords, such pages are useful.