One book that really helped me in discovering ideas for my world building is a book called Guns, Germs, and Steel by Neil Diamond. It was the required reading for the world building class I took at my university last semester. It presented a lot of explanations as to why Earth is the way it is now, and I took some of those explanations and applied it to my world, while I took others and bent them because there's magic in my world that would change the results.

I also find inspiration through reading about various cultures throughout Earth's history and taking aspects from them and molding them to fit within my own. I just look around Wikipedia or I browse National Geographic until something catches my attention.

I am fortunate that I live in an area with a large science fiction and fantasy community, so when I can, I attend the various cons and writing symposiums that are held around here. They have a lot of panels on world building and coming up with ideas. Try looking for similar events around you, if there are any, and try to attend. If you are a student, try looking for discount tickets too.

Finally, what helps the most is being able to find others to bounce your ideas off and perhaps they can give suggestions on how to make it even better. Of course, being part of this tribe is the perfect place for that.

I personally do not take any inspiration from books or movies I have watched or read. I usually make up my own strange and somewhat entertaining theories about life and random things about this universe, then string together an abstract world with the help of all those theories and thoughts. I am actually writing a book about that, it is titled "Octa", just how my universe is called.

The progress has been slow though...page 40 from 200+ and I've been writing for over a year now...sooo much typing^^

I don't know how helpful this is, but I usually base my worldbuilding on ideas for storytelling that are sort of woven together. What this means, I guess, is that I have some idea for a story (that I will probably never actually write) and that I think about what the environment that that story takes place in ought to look like. Then I take several of these sorts of things and put them together into something that's more coherent, modifying things along the way.

As for where the "inspiration" actually comes from, I'd say it's essentially just a mix of media that I like: I was a big fan of Garth Nix's Old Kingdom series, and I find compelling various themes, tropes, and interactions that come from novels, t.v. series, anime, etc.

I dove into world building the day I had a dream about this massive, sky blue bird flying. That was the whole dream. Soon he was the Aslan figure in my world and I had a story setting about a Depression-esque country from which the hero would journey blah blah blah.... Soon it developed and a year later it's a solar system with a history that I keep revising.

Inspiration also comes from "What do I wish this reality was like?" and then you change it. I wanted my characters to be able to breathe in space. I wished we had background music. Insects are annoying. Etc. Now there's enough air in space to breathe, the air emits background music pseudo-magically, and there aren't any bugs or rodents on the main planet. I'm very free wheeling when it comes to creation. A lot of people want things that make sense down to nitty gritty details. (I learn a lot from them.)