Here is a wealth of background information on common phrases and allusions, encompassing everything from "rebel without a cause" and "Marlboro Man" to "The Twelve Labors of Hercules."
Drawing on Oxford's unrivalled bank of language and quotation on-line resources, this highly browsable potpourri of allusive terms includes entries from a broad range of topics, including classical mythology, history, religion, folk customs, superstitions, science...