The Cook's Companion , by Stephanie Alexander.
Probably my first proper recipe book purchase, about a year after it was first published I have had a few recipies not quite work out of this one. E.g. pancakes, and a friend didn't have much luck with the peach pie. However, I have had some success and 'favourites', crop out of this book, like pesto, bbq chicken wings and lamb roast marinade (the lamb roast itself was terribly undercooked according to the weight/time/heat ratio that she offers).
Thai Food , by David Thompson I bought this for myself a few years ago, coveting the pretty pink silk cover, and the fact that it came with TWO inbuilt ribbon bookmarks, not just one. I tried to read this cover to cover, and only made it through the introduction and lengthy descriptions in the first half of the book. However, after having owned this one for a year, and not really having cooked from it, I made the resolution not to buy any more cookbooks. Generally I use this one more as a reference, to look up the composition of dishes that I have enjoyed at thai restaurants. E.g, "Nam dtok", after I sampled this at the Jindabyne thai restaurant. Dishes that I have tried to cook from this with varying degrees of success have been: tom yum (much better if you don't substitute everything out of it), vietnamese dipping sauce, and green papaya salad.
The Complete Asian Cookbook , by Charmaine Solomon. A friend of mine was given a copy of this almost ten years ago, and I have coveted it ever since. I read it cover to cover whilst sitting in her couch! I later received it as a gift one Christmas. I use this as a handy reference for some Asian ingredients, looking up undecipherable ingredients that I have found on the back of some packets. I haven't actually cooked a dish from it. A handy tool is the index in the back which has lists of alternative names for ingredients. My one gripe is that it needs more illustrations. Having accidently bought warrigal greens once, it took a while to identify it from this book.