So you might not think it’s worth your while. And substantively, it may not be. But can Wikipedia speak to you? Knol can. Sometimes.
If you browse Knol’s catalogue of user-submitted articles (a number of which duplicate content from Wikipedia, but that’s another item for another day), you will find that audio tracks are few and far between. Yet, when you do encounter one or two or more, as Alex Chitu of Google Operating System discovered, you’ll find that the computer-generated vocal portrayal of test on a page is surprisingly tolerable. Noticeably fake, yes, but not terrible. Here's an example.
Where the pace of a text-to-speech rendition goes most awry is with abbreviations and acronyms and so forth. Also, the speech system doesn’t make very noticeable distinctions between paragraphs, sections, or chapters. Otherwise, it’s not half-bad.