Design*Sponge had a tutorial a while back from Julia Rothman. It was eye-opening to me because I have always made patterns digitally by applying the principles I learned in our 9th grade geometry class unit on M.C. Escher (essentially, take a shape away from one side, add it to the other, ad infinitem). And while this works for me, I think that sometimes the effect is too linear. Julia Rothman's approach is more low-tech, i.e. pen and paper and some paper cutting sleight of hand, but really satisfying. I think it results in a more organic feeling pattern, which is definitely something I want to explore more.
So, like any good nerd, I have also started reading this book,
Pattern Design - A Book for Students Treating in a Practical Way of the Anatomy, Planning and Evolution of Repeated Ornament by Lewis F. Day, published in 1903. With a title like this, it's hard to understand why this one isn't flying off the shelves, I know. But if you are interested in pattern and surface design, OR you just like really bitchy snark about bad wallpaper, you must read this book. Mr. Day has, as they say, quite a literary voice and an opinion or two which may or may not condemn the vast majority of all design. But better yet, this is a really informative book about the science of satisfying pattern design. Say that three times and see if you don't get a little hot and bothered. And, AND: big chunks of the book are available online, so that even if your library's 63 copies are all checked out, you can get hooked up with the patterny goodness posthaste. Do it. Your ugly wallpaper demands it.