I like Thomas Keller's Ad Hoc. None of the pretention, labor, and expensive ingredients of The French Laundry. Just really good family-style foods. If photos aren't important to you, a lot of people like the Zuni Cafe cookbook, though I find that I pretty much never touch it because of the aforementioned lack of photos (I start cooking with my eyes).
I'll assume you want a recent cookbook, though you don't say that. Probably the book I got this year that I am most impressed by, both for reading and cooking from, is Dorie Greenspan's "Around my French Table'.
Others I've enjoyed a lot this year:
Vegetarian: Plenty by Yotam Ottolenghi
Every-night dinners: HIgh Flavor, Low Labor by J.M.Hirsch
Italian: Stir by Barbara Lynch
The Canal House Cooking books are wonderful
If you don't care how old the book is I have other recommendations. Can you give us some clues on what type of cooking you like to do and some of your favorite cookbooks currently? That will help us know what direction to steer you in.
On my own wishlist for Christmas:
Tender Vol II by Nigel Slater
In the Kitchen with a Good Appetite by Melissa Clark
You might want to consider a past COTM. I've pasted the link to the archive below.
I find it very helpful in that you can take a look through reviews and feedback shared by other Hounds and find books that interest you most.
if you are fortunate enough to get it as a Christmas gift, you can then share your cooking adventures with us by adding to the COTM threads.
I've written about it on this board before, but it's worth repeating here - i love marc vetri's il viaggio di vetri. tons of great recipes, nothing that is overly complicated, but still elegant in a rustic way. cant say enough good things about it. there is a dessert section in it, as in every book, but i don't bake much and i think his desserts are appreciated more from a non bakers point of view - as verti himself creates them along with the apps and entrees.
I think you may need to tell us more - like what do you have already; what style of cooking do you like and what don't you like.
However, for now, you ask what cookbook I couldnt do without. Easy answer - Delia Smith's Complete Cookery Course (first published 1978). I would throw away every other one I own to keep that one.