Anything Sci-Fi. It makes me wonder if there really is anything or anyone else out there. Also, it makes me wonder if we can accomplish any of the depictions in our shows. It peaks my curiosity. Best of luck to you!
Space, the universe and all of that kind of stuff.
Things like this, which is the oldest known galaxy in the universe, or this:
which is a picture of a supermassive black hole, just get my imagination all fired up. This is why I love space :P