I just finished reading The Circle Maker, by Mark Batterson. (Thanks for the gift, Mariann. I am constantly amazed at how God brings new people--and just the right gifts into your life when you need them!) It was one of the best books I've read on prayer in a long time. Not only was it inspirational, but it renewed my desire to pray and my resolve to "pray through". I loved his examples of answered prayer and the timing of those answers. Sometimes years passed before prayers were answered, but when the answer came it was often "exceeding abundantly more than you could ask or imagine."
The book is so well written with numerous stories and examples included, that I was eager to continue reading but didn't want to finish the book because I was enjoying it so much and feeling challenged to pray in so many more areas.
If you are needing a revival in your prayer life, or if you just need your faith in the power of prayer renewed, I highly recommend The Circle Maker.