FRANK R. PAUL: At a time when most Americans didn't even have a telephone, he was painting space stations, robots and aliens from other planets... he was the guest of honor at the first world science fiction convention, and he was the first person to ever make a living drawing spaceships. What could be cooler than that? via the one and only BLDBLOG, with an interesting take on the subject.
Greg Egan's website, including 17 full stories (my favorite) and explanations (by the author) of some of the science (including quantum soccer) in his books. Not the prettiest site I've seen, but a treat for fans of Egan's brand of "hard" SF.
Orion's Arm is "an interactive hard science space opera, a joint effort in science fiction worldbuilding and a forum for cutting edge science fiction ideas".