Speddings book is a great read, as is Ron Hills epic 2 volume story.
Am reading IronWar at the moment : a controversial but thoroughly gripping look at the relationship/battle of Mark Allen and Dave Scott, two of the best ironman athletes the world will ever see.
Any books by Richard Moore are great, especially In Search of Robert Miller and Slaying the Badger.
Other good ones are First Triathlons, Becoming an Ironman and Running through the wall - all short stories about peoples experiences.
ps: glad people enjoyed mine.