For the past six months I've been taking the totally uncharacteristic step of power walking around my 'aerobically correct' town for between 45 and 90 minutes a day (often, רחמנא ליצלן) at ungodly hours like 5:45AM. When I walk alone, I take my trusty mp3 player with me and listen to music (healthy), the radio (institutionalized depression) or lectures/shiurim (inspiring and very fruitful for footnotes). The latter provides an opportunity to reexperience learning with the Rav זצ"ל and for catching up with what friends and colleagues are saying.
Herewith, some recent choices:
Bergen County Bes Medrash (I especially recommend the Yiddish tapes. For me, who only studied with him after 1967 and in English, they provide an entirely new dimension of understanding and appreciation of my master and teacher.)
Rabbi Eric Levy
Hear the Rav (This is the Rav's shiur on Tefillin de-Rabbenu Tam, blessedly digitalized).
Teachers and Friends:
Rabbi Dr. David Berger on different topics (here, here and here [the last only for RCA members])
Rabbi Meir Lichtenstein on Shemitta (a wonderful, lucid and pentrating discussion).