To be honest, I try very hard to avoid drawing from established sources for my settings. They do, undoubtedly, influence my creative direction, but I strive to draw from my own storywriting ability. I greatly prefer my own material to anything that's published (and the reason that it's a testament to the quality of Penumbra's Nyambe setting for d20 that I use it without modification in my D&D campaign).
Obviously, for established settings like Star Trek or Star Wars, it's difficult to escape what's been previously done, so I build upon "canon" and work my storylines from there. But, I still write my own "scripts."
Davy Jones
"Frightened? My dear, you are looking at a man who has laughed in the face of death, sneered at doom, and chuckled at catastrophe! I was petrified."
-- The Wizard of Oz