Also, not sure if you are familiar with Derek Trucks or not. I feel he is a true genius in the slide guitar world. Here are a few links to some videos of him playing in this style. He has all the blues chops but he also has a wealth of world music influence that make him quite a cut above the rest.

http://www.youtube.com/watch?v=8AkvIErWE8c&feature=related

http://www.youtube.com/watch?v=N65cP52NC8s

Just a few. Enjoy if you have not already done so!