For solicited American Express Cardmembers, earn double points on eligible purchases made between June 1, 2007 and August 31, 2007. See the following links for details:

• http://www.americanexpress.com/doublepoints333: earn double points without any threshold
• http://www.americanexpress.com/doublepoints484: earn 1 additional point for virtually every dollar you spend over the threshold specified in the offer you received

Enroll by July 15, 2007. (Via FW.)