A friend that I'd had a discussion about Aspergers Syndrome with recently sent me this book, and I finished it last night as well. It's a fascinating story of Daniel Tammet about what life is like as an autistic savant. He explains clearly what challenges he faced growing up – and still faces – and how he overcomes them. What's fascinating about the book is how well he can explain what he sees, most notably his synesthesia. What this refers to is that he sees numbers and shapes, and visualizes lengthy sequences the same way. He can even draw and sculpt what the shapes look like. For example, here's how he visualizes the first 20 digits of pi.
He tells a fascinating story about when he was presented with a section of hundreds of numbers from the 22,000 he memorized of pi (that's 3.14 for the rest of us) as part of the filming of a program for TV about him, Brainman. The producers had randomly replaced the number "6" with the number "9" and Tammet realized right away something was wrong – because the shape of what he was seeing didn't like right. He described the shape as looking like a familiar home that had been vandalized.
Great book if you're interested in the subject.