The folks at universitiesandcolleges.org have provided a very handy resource here. They've sifted through the big OpenCourseWare universe and centralized the resources for over 500 college courses. In some cases, you'll find audio lectures. In other cases, you'll find lecture notes, reading lists, and homework assignments. This mega list makes it easy to browse through the different resources without having to skip from one OpenCourseWare web site to another. The page must have taken quite some time to put together. Very glad that they did it.
As a last note, the U&C folks were kind enough to include our collection of Free Courses on their list. Here, you get audio (and sometimes video) lectures from over 200 courses. Simply download them to your computer or mp3 player, and you'll be transported right to the classroom of many fine universities across the world.