Apart from the thoughtful Times of London obituary and Gerald Jonas's extensive NY Times essay*, one of the best tributes I've seen to the late Arthur C. Clarke is Jeff VanderMeer's write-up on Omnivoracious. The blog post includes a reaction from Del Rey editor Chris Schluep, who was in Rio de Janeiro when he learned about Clarke's death: "I can't help but think that without his ground-breaking work on satellite technology," Schluep reflects, "it wouldn't even be possible to have heard the news and provide such an immediate reaction." True, that.

*Which has one very surprising error, for someone as well-versed in science fiction as Jonas; can you spot it? (Hint: It's not directly about Clarke.)