The design that pops up when you add a hyperlink, image, etc... is it just a random design? Or is it from sci-fi storyline?
This is a custom design by Jin, Stack Exchange's resident designer. You can see a smaller version of it on the top right of the site's background, and the site's favicon is a stylized version of it. (There's also a T-shirt, but it's a limited edition only.) See also