It would be nice if HTML could be a format choice, too. I recall the last time it was discussed we couldn't reach a concensus on which fonts/colours to use which would enable everyone to view the story. But if it was simply another choice of format, among others, rather than the only choice, then I think that issue would be less important.
I know there are a few sites that can change the font/background colors with a drop-down menu (fanfiction.net has recently done this with a dark/light option). It's a fairly simple javascript that can be added to the HTML pages.
I don't know if space is an issue on the archive, but I was recently looking at how to make PDFs on the fly. ezPDF was one option, but I was having problems getting it formatted. The drawback is that every file is formatted the same way (single column, double column, etc). It can pull the format out of the original file, though, so if it's converting an HTML file, it can convert all of the bolds and italics.
