If you haven’t seen Wikipedia it is probably one of the most comprehensive information sources on the planet. I’ve been thinking lately that it would make a lot of sense to be able to listen to that info, and I may still do something with that. But check out PediaPhon
The voices aren’t good, but neat idea. Of course, the best way to listen to articles of interest and actually get decent voices you can stand to hear would be to grab the text with TextAloud and some of the Premium Voices.