The Wall Street Journal's Real Time Economics blog asked the Feldsteins, Shillers, and Mankiws of the world for suggestions on the best way to spend $8 a week--the amount most Americans will see added to their paycheck as a result of tax credits in the stimulus bill.  Here's the response of Adam Posen, of the Peterson Institute for International Economics:

Invest in human capital through existing institutions: buy $8 of cupcakes at the PTA bake sale; attend a lecture at a community college ($8 admission); purchase a book on personal finance or retraining - any of these get spending into the economy with no lag, but also improve your or your family’s future productivity.

The whole post is a must-read.  Get it here.