Like, ideas for you or other people's ideas?
Because, if you're asking for yourself it kind of defeats the creative writing process, you need to have your own ideas, not rely on other people's. Inspiration from other things/people is fine, but if you can't come up with ideas for a fictional book yourself then I wouldn't bother writing one..
In terms of non-fiction, it really depends. Is there anything that you could write about that doesn't already have loads of representation in the book world? If you're looking for ideas, maybe try buying one of those books that give you a spark to begin with, you can get them in the skill sections of most bookstores. Alternatively, just try writing and see whatcomes out. I've read that the best way to get inspired is to just start and keep going. Once you start producing stuff you'll have more ideas and your writing process will improve!
Good luck