Martha Barnette, the host of public radio's A Way With Words, recommends these books on language, written by some of her favorite guests on the show:
Born to Kvetch: Yiddish Language and Culture in All of Its Moods by Michael Wex
Word Origins ... and How We Know Them: Etymology for Everyone by Anatoly Liberman
Crossworld: One Man's Journey into America's Crossword Obsession by Marc Romano
Do You Speak American? by Robert MacNeil and William Cran
And one more by her predecessor on the show:
The Big Book of Beastly Mispronunciations by Charles Harrington Elster