The bad news is that the existing interface is very mouse-oriented and there is no text-to-speech support.
The good news is that the system, and each part of it, is small, so if you don't like something it can be replaced. Unlike Windows or Unix, where you can't do much about the windowing system, in Plan 9 you really can replace it and it's not that much code. The bad news is that support for whizzy AJAX browsers, etc., is unlikely soon. Is there a university near you which has a CHI/HCI (Computer-Human/Human-Computer Interaction) degree? It might be possible to find a student or two looking for a way-out thesis project and help them design something interesting. Where are you located? Dave Eckhardt