Voice and visual interfaces for non-literate groups

There is much to be learned about creating interfaces for non-literate populations. Since this is not a group that most companies target, very little hands-on research has been done with non-literate user groups. Most of what I have learned is theoretical, based on user research on sight-impaired users, or is from very limited case studies. Some of the best information has come from other the projects of RDVP fellows and the work they have done. (Thanks, Aman.)

Does anyone else have any experiences they can share in creating voice or visual interfaces for non-literate groups? I am preparing to run a research study with other members of Professor Clifford Nass's experiment design group. We want to contextualize the research in realword problems. Any stories would be appreciated.