"Quiet: The Power of Introverts in a World That Can't Stop Talking," by Susan Cain, would make a great Christmas gift for anyone who is quiet, shy, retiring, sensitive, stimulation-averse, or, in a word, introverted. The author herself is an introvert, which is why she started researching the topic.
(Or, if you're an introvert married to or working closely with extroverts, you may even want to give a copy of this book to him/her/them to help him/her/them understand why you're just fine the way you are, thank you very much.)
What she found is hilarious (Harvard Business School---what a bunch of clowns!), endearing (Franklin and Eleanor Roosevelt---why cool is overrated), educational (The Secret of Public Speaking for Introverts--and also walking on coals), and helpful (Warren Buffett, your shy children, and the communication gap).
Yes, you introverts, among whom Madame L includes herself, if you feel out of place at Harvard Business School or at a cocktail party, it's not because there's something wrong with you. (There's nothing wrong with extroverts, either; it's just that they're not the end-all and be-all that your elementary school teacher thought they were when she tried to turn you into one.)
There IS a place for you in the world, a place which you can find and feel very comfortable in, if you can ignore the people who want to keep trying to help you pull out of your shell.
This book combines research, personal insight, history, and great writing to cover the topic thoroughly and without too much dilution of the research.
"Quiet" is available in hardback from Amazon.com for less than $16.00 and in paperback for less than $11.00. Madame L borrowed a copy from the public library after waiting for four weeks for it. She didn't get to finish the whole book, just reading the first half and parts of the last part closely and skimming over the rest. She may go ahead and buy her own copy when she can get it used.
(Note to well-meaning friends and family: Please do NOT get this for Madame L for Christmas because even though she enjoyed it and mentioned that she wants to read the whole thing eventually, and thinks it would be a great gift not only for introverts but also for their puzzled extroverted friends, she has a pile of books THIS high which she will be reading first...So, really, she will get it used, someday.)