But neither RTF nor PDF is acessible
This statement is misleading if not false. I have a visual disorder and concerning accessibility I would think the web being primarily a visual medium those would be the accessibiltiy issues.
There are many text to speak browser/readers that read rtf just fine. But, I am amazed by the new generation of pdf acrobat readers (FREE) that have a built in text to speak engine. AdobeAcrobat7 is such an animal. If you are looking to creating stand alone documents that is the way that I would go. In fact the newer versions of word, wordperfect, open office all have a save to pdf function. Those are probably bundled on your desktop, so there is no need to buy any addtional programs. Cheers. William