Anne Ryan (no relation... I think) is one of my favorite illustrators (and authors) and her website is one of my favorite websites! The main page is fine as far as those kinds of things go, but that's not where the magic is. For that you have to go to the Illustrated Notes link, where you are taken on a fascinating and unique journey into her creative process and how she works and reworks her stories and artwork into finished books.
Anne shows not only how she finds inspiration for her sketches, but also how she transforms those sketches to match the tone and theme of her stories. She even has examples of how she re-works, edits, and lays out the text of her stories using an example from her latest picture book "Unforeseen Circumstances", among other works.
I actually find myself more drawn to Anne's rough sketches than her finished art, although her style often incorporates elements of both.
It's something I try and do on this site, specifically in the "Sketches" section, where I show the really rough pencil or ink sketch next to the more finished (if you can call it that) artwork.
There is also a great video about Anne where you can see her studio, which is also one of my favorites of all time.
I mean, seriously, everyone should have to climb a ladder to go to work!