Wordhoard is free software for finding the numbers of words in etexts, using morphological, lexical, prosodic, and narratological criteria.
I'm not going to say that everyone needs this, but I think there are people on my flist who would love it dearly. This is like ngrams, only ever so much more so. "Looking for love" shows what you can do with Chaucer, Spencer, and Shakespeare-- for example, finding out whether men or women in Shakespeare talk more about love (the program is able to combine the same word in its various verb tenses etc.).
An entertaining discussion of how the developers worked out Mac vs. Windows issues.
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