Goddamnit. I never met McDuffie and I never read enough his work, but I enjoyed nearly all that I did and while he was never on the V that much, it was always great when he popped up. The first comic of is I ever read was this one, containing a West Coast Avengers story that was better than such a story should have been:

Eventually, I dove through back-issue bins for Damage Control, which is just fabulous book Marvel never did enough with. Like everyone else, I loved his time on Justice League (Unlimited), but I'll go further-- he saved that show. Without Dini, Timm and his compatriots seemed to have no idea what they doing and nearly every two-parter felt way too stretched out bloated. When McDuffie came on, that changed almost at once, and by the time the show switched formats to Unlimited, it was one of the best things on TV.
I'll also always remember the look behind the curtain he gave us into his JLA run, which was just shocking. His struggles against racism in the comics industry came mainly when I was too young to pay attention, but those posts are something I'll never, ever forget. I wish more creators had the balls to speak out like that.