Best of the Left Podcast is one of my favourites. It "aggregates and amplifies" clips from various left-leaning shows and podcasts (including The Daily Show, Colbert Report, Rachel Madow, Real Time, Young Turks and a bunch of others). There's even a one or two dollar BOTL app you can buy that lets you stream the show on 3G wherever you are.
Music clips relevant to the topics fade in and out to transition between clips.