This is pretty excellent. It's a chart, created by Paul Rosenberg at Open Left, that combines data from Moody's Economy.com and Dean Baker's Center for Economic Policy and Research. It shows the return on investment for different stimulus options.
The takeaway? Food stamps, unemployment benefits, and infrastructure investment put the most money back into the economy for every dollar spent on them. Tax cuts for corporations and the wealthy do the least. (A payroll tax holiday, which is essentially a tax break for poor people, isn't so bad.) Job creation maps similarly.
So when conservatives tell you that FDR's public investment programs made the depression worse and that we need to hold fast to the conservative economic principles that created the current mess, shoot them this link. Perhaps President Obama should use that snazzy new BlackBerry of his to email it to his Republican opponents in Congress.