Let me start by trying to dispel a common misunderstanding. "Text-friendly authoring" isn't in the least about eviscerating your web documents by cutting out all the other media such as images, sound, executable code etc. On the contrary: the intention is to use the appropriate media for each purpose, and to use them to the full; but to avoid those other media getting in the way for readers who cannot use them. Nor is it about creating a complete additional text-only version of your site: that might, very occasionally, be justified, but I don't recall meeting a situation where I would have chosen that approach myself, and have reviewed quite a number of examples of other authors doing this where I came to the conclusion that their approach had been misguided [1].

http://ppewww.ph.gla.ac.uk/~flavell/alt/