Machine Learning by Thomas Mitchell
This book is a classisc and a must for anyone who want to learn about machine learning.
Artificial Intelligence : The Modern Approach by Stuart Russell & Peter Norvig
This is a book that touches on a lot of topic on AI and machine learning. This is probably the closest to "Code Complete" of AI. Peter Norvig, one of the authoer, is now working at Google.
There are a lot of sub-fields of AI including Machine learning, Data mining, Computer vision, Pattern Recognition, Natural Language Processing, Genetic Programming and etc so I probably could not list all the books here but if I have to pick some of the most influential books, I would pick the two above.