Mountaincraft and Leadership by Eric Langmuir was on my University course (Outdoor Leadership) reading list, I managed to find a 2nd edition in a dusty corner of an old book shop in Keswick for only £4. Saying that - It has been thumbed through more times than most of my other books and the newest edition has updated pictures, diagrams and even more information.
It's not a book to read from cover to cover but it has a wealth of information for anyone who enjoys the outdoors, whether leading a group out on the mountain or using it to go over the basics of weather prediction while out canoeing. Dip in and out, read the whole section on snow shelters, or keep it on the book shelf to remind yourself before going out to play in the snow this winter - a handy book for anybody.
If you are planning a career in the outdoors or you are already on the Mountain Training ladder this book is invaluable. Revised and published by MTE and MTS this and the Mountain Leader Summer handbook will give you a head start for any qualification - I have used the weather section before canoeing assessments, navigation before mountain bike skills days and security on snow before a long winter weekend in the Cairngorms.