Here is a wonderful collection of 100 Studio Ghibli images, collecting some of the best background paintings, and animation stills from their films:
If you like what you see, I highly recommend any of the Studio Ghibli 'Art of' books. They are all fantastic, and they release these books consistently for each film, which makes for a wonderful collection:
I would also highly recommend the book, 'Studio Ghibli Layout Designs', which collects a TON of layouts from a multitude of films. This book is a little harder to find, but well worth the time and expense. It's a lot of book.