I just noticed this is a forum in relation to gravelly voices from around the world. Well try Zewditu on the last Invisible System Ethiopian/Jamaican/UK fusion album. I have never worked with such a gravelly voice, especially an Ethiopian female one and it is not to everyone's taste as it is that gravelly. But I love it! As did many reviewers.
Best places to start are youtube where you can watch some of the tracks being made in my studio in Addis, Ethiopia where I recorded and setup Invisible System and Dub Colossus album1.
http://www.youtube.com/user/danieleonha ... ature=mhee
And myspace, facebook player on Invisible System pages, spotify, amazon, itunes etc for audio. The second album Street Clan has Zewditu on. She is a stormer! :)