May I just say that I have been a huge fan of NPR/PRI for as long as I can remember… probably since sixth grade or so… In particular, I believe I have heard every single episode of This American Life… all 200+ of them… You too, can hear almost all the episodes- not at all a bad use of your time- because a majority of them are online for free.
As for NPR: All Things Considered, Morning Edition, Weekend Edition… all good. Quality radio that I enjoy.
That being said, I also have a pretty unhealthy obsession with Howard Stern. I have stockpiled a fairly complete collection on CD-ROM of his shows from the past few years. I have a whole other pile of shows and clips from various years prior.