The Buddha's Teaching: An Introduction by Thanissaro Bhikkhu
This book is freely available at Dhamma Talks. It is a short introduction to the teachings of the Buddha. Thanissaro Bhikkhu does not go into much detail, if you are looking for a detailed introduction this is not the book for you. However, it is easy to read and you will get some decent information from it.
I found that it rehashed all the information I already knew. In some cases, it helped me see something in a different way and understand it better. I think I will read it again and I would recommend it to others but I would tell them that it introduces you to the philosophy of Buddhism more so then the teachings of Buddhism.