I've been meaning to post some of these links for a while... The internet is a fabulous, horrifying thing, alternatively disgusting, provocative, entertaining, and informative. For the moment, let's ignore all the other bollocks and focus on "informative."
Let's say it's been a while since college, or maybe you never went (or, like me, you're just curious to see how other professors "do it"), but you're self-motivated to do some learning/thinking on your own. You can now find free university course content from some of the top researchers and lecturers in the world on the internet. If audio is enough for you - perhaps you just want to listen to a Harvard professor pontificate about Shakespeare on your Ipod while you go for a morning stroll - they try out iTunesU.
Personally, I found it too distancing. I think it's overly optimistic of me to presume that I can clean the house or exercise while simultaneously paying attention to Robert Sapolsky.
Instead, I think that Academic Earth has more potential. Here, you'll get video feed of the lecture as well as audio. So, minimally, you'll be able to see the professor in question. Unfortunately, they still haven't solved the problem of how to nicely synch-up lecture slides with audio presentation (a certainly jump-able hurdle). Sometimes, the videographer completely ignores the slides which make science lectures, in particular, nearly incomprehensible.
If the stodginess of Academic Earth is too much for you, you can also try a couple of other websites that offer more intimate and, periodically, controversial snippets from so-called experts. Both Big Think and FORA.tv offer interviews and speeches from prominent members of the world community, on all number of topics.
Big Think features direct interviews conducted by Big Think staffers. For example, here's Helen Fisher, whose theories on romance, sexual attraction, love and lust play a role in some of the research I conduct:
FORA.tv, in contrast, typically posts speeches and interviews captured in other contexts. The pieces can be unsatisfyingly short, which I think is catering to the presumed short attention span of their internet audience. For example, a male beaver's lament:
Go forth and nerdify yourself!