Does anyone know where I can find a source for free plaintext or xml natural language dictionaries. I am working on a program for memorization and I'd like to make some examples.
I suppose by "dictionary", you mean just a database of the words that make up the language? If so, I'd try the dictionaries shipped with open source spell checkers like aspell. Also take a look at this Super User post, you may be able to use the dictionaries from some of the open source tools mentioned there.