It isn't easy though to pick the right ones, those that are really worth listening to.
I will point out some interesting ones in this blog, hoping to get some new suggestions too.
Medpod101 already has two podcasts: the DermPod and the MedicinePod, which has almost 30 episodes already, around 15 mins long. Dr. Jacob states that they are not designed as lectures but as case presentations, in which a patient is simulated and the case is in the end resolved. The patients are made humorous on purpose - infact I find that the one who has Pneumonia really seems a close relative of Borat.
If you are familiar with iTunes I really suggest you to subscribe to this podcast and start with the cases you are most interested in (Asthma, UTI, Hypokalemia, Tachyarrhytmias, etc.)