While I'll admit moving away from 3.X based games a bit ago and returning more to my gaming roots mechanics-wise, one campaign setting that came out towards the end of 3.0 was one that I had a blast playing/running and wish had continued longer. That setting was Dragonstar by FFG.
Sadly I think timing was what killed the setting. 3.5 came out right after it was released and I believe d20 Modern as well, which caused the mechanics to perhaps be seen as "dated" by the masses. Some of the later books for it were not as good as the original books, but I grabbed everything I could for it and even worked up my own stuff.
Sure it was "D&D in Spaace!" but why is that a bad thing? LOL