FA Hayek's classic The Road to Serfdom typically sells around 7000 copies a year. The year Barack Obama was elected President, it sold 30,000 copies. Recently, Glenn Beck did a program about the warnings contained in Hayek's book. The following week, the book sold 70,000 copies. Yes, you read that right - 70,000 copies in one week.
From the NYT Bestseller Inside the List column:
"After Beck’s program, the book sold about 60,000 to 70,000 copies in one week. This surge came too late to push the book onto this week’s paperback nonfiction list, which records sales until June 12. But stay tuned."