Dave DiCenso – De-Mystifying Rudiments & Applications (DRUMEO)
Here's an excellent (and lengthy) lesson featuring the six-stroke roll in some interesting ways. Dave DiCenso is an absolutely awe-inspiring drummer and a teacher. I love this guy. And you gotta love DRUMEO for offering these clips for free and including the lesson notation (5 pages!).
I'll be working on this stuff for quite a bit, and there's a good chance I'll pick up his book.