i'm really into history. (when i was growing up, i wanted to be an archeologiest or palentologist as many of my friends did after we saw indiana jones and jurassic park)
but seriously i do enjoy learning about history and sociology
so i'm totally addicted to the podcast "stuff you missed in history class" by howstuffworks.com
they vary in time (up to twenty five minutes long) and have a full range of interesting topics from the 1916 shark attacks on the jersey shore (close to my heart) to "who were the other two men on the ride with paul revere" anyway, i suggest you check it out. it makes my gym time go a lot faster.
i'm also listening to "money girl's quick and dirty tips for a richer life" which is a fun eight min. podcast dealing with everything from budgeting to 401ks. i have read numerous financial books over the past few years, so a lot of this is old hat to me but i find it very helpful to listen in anyway because it helps keep me focuses on it.
Also, "stuff mom never told you" is pretty good too, though i like "stuff you missed in history class" more.
"grammar girl's quick and dirty tips for better writing" is also a very good podcast. sometimes it's nice to brush up on your grammar. they are not long, at the most ten minutes, and grammar girl isn't preachy. and it's got a good theme song.
happy listening!