I hadn't thought of doing many book reviews on the blog, but I am all about saving money, and if you're a home owner (especially a new one), one of the best things you can get for yourself is one of these:
I found one at the library not long after we moved in, and immediately decided to buy one to keep on the shelf (as well as getting their Home Improvement guide, and getting the Repair guide as a gift to other new homeowners). Obviously, there's loads of potential savings in here, but what's made it one of the best investments I've ever made has been with plumbing.
Twice now--first in the kitchen and then just today in the upstairs bathroom--we had a serious clog in the sink. Fortunately, both times I was able to take apart the pipes underneath, clear out the obstruction, and get it all back together by myself. The first time, it absolutely saved me the cost of bringing in a plumber to deal with the problem (today's clog was bad, but not to the same severity as the one in the kitchen had been). Given the cost of the book in relation to the price a plumber would have charged me, this book has already shown itself to be the best investment I've ever made.