With Comic-Con last week and all the summer block-buster movies and me just being a natural nerd, I can't help but feel drawn again recently to very mod, science fiction-feeling elements. Not anything too obviously science fiction-y, just an affordable touch you could add to an existing space.
While my dream might be to live on the minimal and mod sets of Forbidden Planet or 2001: A Space Odyssey, it's not entirely feasible for me to forego everything we own and replace it with sci-fi themed items (my roommate, for instance, might not appreciate waking up on a spaceship every morning).
However, that doesn't mean I can't look for a few elements to throw into the mix. High-gloss bold colors, sci-fi shaped tables, retro-style sofas, recognizable light fixtures and more can all do a great job hinting at the fact that you're a science fiction fan, especially when combined with a few other similar subtle sci-fi pieces (and perhaps even a space travel-themed poster).
(Images: As credited above)