Markov Chain toy - grab some text as input (a file or a text box); allow the user to select whether they want to operate on words or letters; allow the user to select what 'depth' they wish to use (two word groups, three word groups, etc.); generate your probability tables; then spit out some output text.

being able to mash more than one text source might be nice.

bonus points if a user could just point the tool to a webpage to generate 'parody' version.