A podcast that has many people excited is The Tolkien Professor (feed). Professor Corey Olsen from Washington College teaches the works by J.R.R. Tolkien in a way, as he claims, would have been approved by Tolkien himself. I know people who do the readings before they listen to the next podcast - that shows how involving these lectures are.
From time to time Olsen invites guest speakers and one of the regular listeners alerted me to one of them: Michael Drout (download). Drout is a philologist just as J.R.R. Tolkien and aside from studying the same subjects, he studied the work of Tolkien from a philology perspective. He starts the lecture by reciting Beowulf, as Tolkien would start his, and kicks off from the text and the words of Beowulf, taking it to Tolkien and to the Lord of the Rings from there.
The point Drout so elegantly and entertainingly makes is that specific words and philological mysteries in texts such as Beowulf force the philologist to make wide stretching assumptions and conjectures. In that process, when he has to leave the realm of science and more and more enters the world of imagination, as a philologist he has to stop. Tolkien would not stop. And so, Drout argues, in order to give the words he struggled with a life, he invented a whole world for them. And he gives a number of examples from both Beowulf and Tolkien's literary work. Even if you are not into following the entire course, at least pick up this bonus lecture.