Text Generators from SourceForge

Available for download here. All of the generators are in a single .zip file. Once unzipped, you will find several folders, each containing html files. To use the generators on your own computer, open the index.html file (if there is more than one file in the folder). The generators use embedded javascript, which will work on any PC, Mac,or Linux system.

Or you can use the versions I have installed here:

CharNG
An n-gram generator/analyzer. This will cut up any selected text into selections of "n" letters, from single letters (unigrams) to 10-letter sequences (10-grams). Several other settings allow for adjusting line lengths and such.

Further documentation and implementation notes.

I pasted in the Wikipedia entry on "n-gram":

In the fields of computational linguistics and probability, an n-gram is a contiguous sequence of n items from a given sequence of text or speech. The items can be phonemes, syllables, letters, words or base pairs according to the application. The n-grams typically are collected from a text or speech corpus.

and got this:

the fields or speech 
         collected from a text or speech 
collected 
     from 
       a text or 
speech. 
   The fields or base phonemes, syllables, syllables, syllables, syllables, syllables, syllables, syllables, 
         syllables, syllables, 
        syllables, 
syllables, 
   syllables, syllables, 
      syllables, syllables, 
syllables, syllables, syllables, 
  syllables, syllables, syllables, 
syllables, syllables, syllables, syllables, syllables, syllables, 
syllables, syllables, syllables, syllables, syllables, 
     syllables, 
      syllables, syllables, syllables, 
syllables, syllables, syllables, 
syllables, syllables, syllables, syllables, syll

eDiastic

This is based on Charles Hartman's DIASTEX, an algorithmic implementation of MacLow's diastic technique.

To use this, select an "Input Text" as your source material (such as Woolf's The Waves), then select a "seed text" (such as "ridiculous in Picadilly"). Set the other parameters as you see fit.

Further Implementation notes

jGnoetry
This tool allows you to generate couplets, haiku, sonnets, etc from several "corpora" (source texts).
Implementation Notes

WpN
Based on Oulipo practices, this allows you to do "n+7" replacements (replacing a word with the 7th word after that word in a dictionary, or any other selected corpus). This one's fairly complicated, so here are the Implementation Notes