Rumor has it that Keith Richards' signature style was lifted from Ry Cooder after the sessions Ry did with the Stones.
I don't know the veracity of the rumor, but it could have some weight.
Oh, and try anything by Robert Randolph & The Family Band. They're kind of a gospel/blues/rock style, but Robert is absolutely blazing. And he plays a pedal-steel guitar, not just regular slide style.
Another similar slide/hybrid guy is Junior Brown. He's traditional country, but he plays a double guitar - regular 6 string and pedal-steel. He's pretty amazing as well.