The Tightwad Gazette
I think Amy Dacyczyn takes frugality a bit too far in her 1992 book the Tightwad Gazette, but it is still a good resource for frugal ideas. Admittedly there are going to be a lot of things most people have already thought of, and a few things (like dumpster diving or reusing the elastic from underwear) that are going to be going over the line for others, but the recycling tips, up-cycling ideas, and recipes will come in handy for most of the population.
I can’t help but think of how clever I was to pick up this book used, at a Goodwill outlet for just a few dollars.