Bhalla, Jag.
I'm Not Hanging Noodles on Your Ears and Other Intriguing Idioms From Around the World.
National Geographic (June 16, 2009)

A fun collection of idioms around the world. Valuable to the conlanger in getting one to think how their conlang/conculture handles situations like the ones illustrated here. There is an interview with the author available from The World from Public Radio International.

Comins, Neil F.
What If The Earth Had Two Moons? And Nine Other Thought-provoking Speculations on the Solar System
St. Martins Press (2010)

Prof. Comins provides various detailed scenarios of "alternate" Earths. While not a conlanging resource per se, the book (along with his first book) provides intriguing environments within which one's conlang-speaking denizens could reside.

Crystal, David.
How Language Works
Avery (2007)

David Crystal is a prolific author and How Language Works provides a broad view of everything from language's origins to how it reveals social status and degrees of politeness.

Deutscher, Guy.
The Unfolding of Language: An Evolutionary Tour of Mankind's Greatest Invention.
New York: Metropolitan Books (2005)

Lively and highly readable, Deutscher manages to convincingly show how the complex structures of modern languages evolved through simple processes. For anyone interested in creating a family of fictional diachronic languages, this book is a must-read!

Conley, Tim and Stephen Cain
Encyclopedia of Fictional and Fantastic Languages
Greenwood Press (2006)

Highlights more than 200 entries on conlangs and their creators.

Kenneally, Christine
The First Word: The Search for the Origins of Language
New York : Spiegel & Grau (2009)

An entertaining look at the biological origins of language and highlights of current research into this often-overlooked area of language development.

McWhorter, John
The Power of Babel: A Natural History of Language
New York: Harper Perennial (2003)

While laying out how languages mix and mutate over time, linguistics professor John McWhorter reminds us of the variety within the species that speaks them, and argues that, contrary to popular perception, language is not immutable and hidebound, but a living, dynamic entity that adapts itself to an ever-changing human environment - from the book jacket.

Okrent, Arika
In the Land of Invented Languages: Esperanto Rock Stars, Klingon Poets, Loglan Lovers, and the Mad Dreamers Who Tried to Build A Perfect Language
New York : Spiegel & Grau, 2009 (pbk, 2010)

Okrent's book is an enjoyable romp through the history of constructed languages, providing an excellent introduction for both conlangers as well as the general public. The book won rave reviews upon its publication, and Arika was featured on a number of talk shows and in many articles (For a list of press coverage links for Arika's book, click here). Arika also participated in the 2nd and 3rd Language Creation Conferences.

Parkvall, Mikael
Limits of Language: Almost Everything You Didn't Know You Didn't Know about Language and Languages
William James & Company (July 2008)

Parkvall's work is a catch-all of language trivia and information. It contains a small section on conlangs but also a wealth of other useful and interesting facts. The calendar is especially interesting.

Pinker, Steven
The Language Instinct: How The Mind Creates Language
New York: W. Morrow & Company, 1994 (pbk. 2000)

The Stuff of Thought: Language as a Window into Human Nature
New York: Viking, 2007 (pbk. 2008)

Words and Rules: The Ingredients of Language
New York: Harper Perennial (October 24, 2000)

Yaguello, Marina
Lunatic Lovers of Language: Imaginary Languages and Their Inventors
Athlone Press, (2001: reprint)

"This book examines the creation of imaginary languages in history and fiction as an expression of the search for an original, primitive or universal language." Originally published in French with the title Les Fous du Langage: Des Langues Imaginaires et de Leurs Inventeurs