NaNoWriMo suggests you "scramble" your novel prior to sending it in for verification. The scrambling process they recommend essentially replaces all letters with a lower-case A. This version is substantially similar, except that it handles Latin characters with accents. (So "cliché" becomes "aaaaaa" instead of "aaaaaé".) You may also optionally maintain case, so something like "Boston" will become "Aaaaaa" instead of "aaaaaa".
This requires JavaScript. Since it uses JavaScript, any text entered will not be sent back to the server.