Joan Konner: The Atheist's Bible
Joan Konner's The Atheist's Bible is a useful companion to Jack Huberman's The Quotable Atheist, although the two volumes do share some material. Konner organizes her book by topic, and it is helpfully cross-indexed by author (each of whom has a brief biography). The book goes by far too quickly, though--a tribute to both the subject matter and Konner's choice of material. Its only flaw of note is her inclusion of these two quotations that I flagged as questionable in the Huberman review:
"Religion is regarded by the common people as true, by the philosophers as false, and by rulers as useful." (p. 74, Seneca the Younger)
"All religious are equally sublime to the ignorant, useful to the politician, and ridiculous to the philosopher." (p. 79, Lucretius)
They both appear to be misattributions from Edward Gibbon:
"The policy of the emperors and the senate, as far as it concerned religion, was happily seconded by the reflections of the enlightened, and by the habits of the superstitious, part of their subjects. The various modes of worship, which prevailed in the Roman world, were all considered by the people, as equally true; by the philosopher, as equally false; and by the magistrate, as equally useful. And thus toleration produced not only mutual indulgence, but even religious concord."
(History of the Decline and Fall of the Roman Empire, Chapter II)