I found too many "single category" books to put all in one post. Here are the rest that I found!
Latvian Mittens: Traditional Designs & Techniques by Lizbeth Upitis.
This story of a mitten tradition begins with an introduction for mitten instruction, in both English and Latvian. Every pattern is written in two languages!
There are complete patterns for some mittens, but rather than just a desciprtion for each pattern shown, there is also a chapter describing the different symbols and their meaning to the Latvian people. There are patterns from different districts. The author walks through examples of different patterns, and then the back of the book is filled entirely with different pattern charts. Of new interest: There's an interesting a looped-fringe right after the cast-on. I will have to try it!
I've been making Selbuvotter Mittens for a while now, so most of my experience comes from that book. This folk-glove/mitten tradition uses more colors, but there are similarities to the scandanaivan mittens (which were often seen in just black and white). I will need to check this out again to go into the pattens further.
Folk Mittens: Techniques and Patterns for Handknitted Mittens (Folk Knitting series) by Marcia Lewandowski
This isn't a one note... this isn't even one region! The book collects samples of folk mittens from all over the world. Although there are some similarities, there are distinct flavors to mittens from different regions. I love Selbuvotter, but although the patterns are varied, there is still a similar feel between the mittens and gloves. With this book, you can make two pairs of mittens in the same colors, and end up with products that do not look like they were made by the same person. (This is an obvious statement, since these are from different regions of the world, of COURSE the design elements would be different, but hey, I'm a scientist. I say it like I see it!)
Hip Knit Hats: 40 Fabulous Designs By Cathy Carron.
I've long been an advocate that someone's first project should be a hat, not a scarf. Why? Knitting in the round is not that hard, and then you get the satisfaction of having a finished product much sooner. It is easy to visualize your progress in a hat, less so in a scarf that you want 5-6' long.
I have never seen a diverse collection of hats in one book like this before. Many of the patterns have a classic appeal, but a couple are quite unique and would get compliments when you wear them on the street.
They have you play with texture, yarn type/size, bobbles and felting. many of the hats would work just as well for men and women. The sections are divided into Caps (10), Buckets and Boxes (11), Berets and tams (6), Witty Knits (8) and Fabulous felted (5). With many photos of some of the hats, you can see how you can achieve different looks with adding multiple colors or novelty yarns.
Great source of inspiration when you are looking for something new to keep your head warm!