Planet Money is unrivaled. It's entertaining and informative, very polished, and is accessible to the general listener without being too basic for actual economists.
Freakonomics is pretty good. The best episodes are ones where they bring on a world class expert in something and just let them talk a while. Although, to be honest, it's been a month or two since they posted anything that looked interesting enough to me to actually download.
And it's not economics exactly, but More or Less is a statistics podcast by Tim Harford, the Undercover Economist, all about spotting bad statistics. It dips into economics with regularity, and is a quick fun listen.