You can actually just /say/ you have written 50k words - it's called an honesty system.
back on topic: I've been partially writing my nanowrimo novel on my palm, using MacNoteTaker, and autoposting to my blog:
http://novel.schinckel.net
see some details via Google, or visit
http://schinckel.net
http://www.google.com/search?hl=en&l...om&btnG=Search