1) "Lend Me Your Ears - Great Speeches In History" by William Safire - Great compilation of the world's greatest speeches. What I love about it is that it gives an interesting anaylsis of each speech.

2) "100 Ways to Improve Your Writing" by Gary Provost - Although it's not just about speech writing, this book will help you understand how to better write and use language in all writing genres.

3) "Speak Like Churchill, Stand Like Lincoln" by James Humes - Fantastic book! One of the better books about speaking I've read.

4) "Speeches that Changed the World" by Smith Davies Publishing - A smaller but just as great collection of well written speeches. Each speech has a short bio and story about the speaker and the time he gave the speech.