Like Susan below, nearly all of my writing stuff is on my laptop computer. For my day job, I work in environmental consulting. I have a MacBookPro that I can take when I travel (like I am right now) and then plug into a super large screen so I can work with several documents at once side-by-side. I also have all of my writing stuff on this computer, but when I get around to my own writing, I usually don't want to sit at a desk. I pile my books around me and keep track of it all on my computer. I work on 3 types of books - picture books, a novel, and nonfiction, but right now I am very much focused on nonfiction because I'm doing a series of books for Nomad Press on the Geology and Geography of the United States (divided into regions). Here's my Finder with my basic folders and one of my chapters on the Columbia Intermontane behind it:
In each of my chapter folders I dump all kinds of stuff: pdfs of maps and pictures, articles I find, notes I've taken from books, early drafts.
For nonfiction, I use the internet a lot. I use it to give me ideas, help me find books that will be useful, sources of maps or other images, and also as references. For this particular series, the USGS website is very useful. But it's such a big site with so many pages, that I want to bookmark the ones I find particularly helpful and may want to include for further interest or as a reference. I keep the bookmarks in folders, usually just by general book and not by chapter. Here's what my screen looks like with bookmarks in my Safari browser.
And here's one of the bookmarked sites open (with gorgeous graphics of the San Andreas fault and tectonic movements through time...I love you USGS...)
Since I'm traveling, I can't take pictures of my home office setup, but I'll try to add that tomorrow.