Mention slide guitar and you think of . . . no, not steel guitar, or pedal steel. Just "slide guitar".
How many think of Ben Harper? He's a pretty good modern student, to be sure (and a heck of a nice guy).
Wait, didn't some of the blues guys play slide guitar? Like that Robert Johnson dude?
If you think a little longer you come up with Bonnie Raitt, Duane Allman, Lowell George, and even Jeff Beck, although for him, like most of the English '60s rockers, including Jimmy Page, the slide playing, while interesting in the context, was not really masterful. But still cool, don't get me wrong.
Bob Brozman is a one-man resource and evangelist for traditional and ethnic slide guitar. Expert in styles you've likely never even heard of, he tours, clinics, and plays constantly, bringing these styles to new people all the time.
Here he is playing a tribute to one of the blues master, Charlie Patton:
And here he is doing some traditional blues in an unlikely style on a National Steel:
Update: To commentor Coyoteville, yes, I meant Beck, not Back. Thanks.