Fascinating book! A rich buffet for word-nerds, a collection of essays on e.g: ASL; the rules of Icelandic naming; the Manx language; details of translating Les Murray's poetry into French; Esperanto; the grammar and syntax of phone-speech; the work of Georges Perec (appropriately excluding the letter "e"); and his own synaesthetic language of number.
(I'm considering the possibility that I have a crush on Daniel Tammet's mind at this point. ?)