I love Radiolab. Jad and Robert are great cohosts - they bounce off each other perfectly.
I highly recommend the podcast as a regular listener.
However, if you're not going to subscribe or mess about with podcasts, may I recommend the 5 best minutes of radio that I've heard this year?
It's the first 5 minutes of their Bliss episode. I've listened to it twice (and then watched the video). Amazing. Fair warning: you might want your headphones - it's a bit loud.