I want bold, italics, indented or otherwise marked quotations, and chapter breaks as new pages. Prefer indented paragraphs to space between, but that's almost entirely a matter of "prefer fewer page turns." Prefer ragged right because I don't like the spacing issues of big words on small screens, but with either halfway decent hyphenation or enough average words per line, I don't care.
I wish more ebook readers supported PML/eReader PDB files. (Was disappointed to find out the Astaks only support PalmDOC PDB; that bumps my decision to buy one farther away, because I have dozens of ebooks I converted to eReader that I'd like to reread, just not enough to go to the hassle of re-converting them.)
Wish we had a (common, open source, easily added to devices) filetype that supported something between plaintext and full HTML abilities. Italics & bold are sometimes necessary for stories; indents or *some* indicator for quotes/callout texts keep the author from having to put extra "***" dividers in, and starting a new chapter on a new page is pretty much how one I mentally separate "book" from "document."
Oh, and the ability to include images is nice.
Quick, someone make an ePub-lite generator that copies
PML's options and ignores other formatting.