thanks, there's some good stuff in that account.
yeah everything does pdf's, but since you can't resize them or there text i think they'd be pretty hard to read on the smaller version of the kindle. i was under the impression you couldn't resize text with plain .txt files either, but it turns out you can, so those are a good bet unless you want to make use of table of contents, for which i believe you need one of the identical amazon formats (.mobi, .azw, .prc) which come in the drm and non-drm flavors. one of the most popular ebook formats is .epub, which kindle doesn't support.
you can always convert stuff from one format to another with calibre (itunes for ebooks) but sometimes it turns out gross, especially converting from pdf.
a non-specific ebook thread would probably make more sense, but i've found lots of those and they're always book-dumps full of pdf's and epub's. i guess txt is pretty safe, i'm just disappointed the net seems to have agreed on pdf as the most efficient way to share books.