You can put many various files on the nook, but .pdfs are the easiest. (I sort of downloaded all the Lost fic and have been working my way through those.)

I'm currently making a list of what I do have. I played around with cached pages and pulled up a few things I did not have today, but the only one that I've having issues with is Particles. (Just discovered I do have The Weirdness saved, it was just in the Read folder, but no luck on Particles or the newest one that was recently posted.)