Are there any particularly good university lectures available online for download as mp3 (or some other audio format)? I am particularly interested in hearing some of the more advanced classes that I didn't get to take in my engineering degree, like compilers, operating systems, AI, cryptography, etc.
There is another question on CS video lectures, but I would like to listen to lectures on my mp3 player.
UC Berkeley offers audio versions of lectures. If you pick a class from the unfiltered list of all classes you can subscribe to a feed which pushes .aac files.
Introduction to Algorithms at MIT's OpenCourseWare:
And really, MIT's OCW in general.
edit: Also, if you go to the iTunes Store on click "iTunes U" on the left, you'll see iTunes U, which is a collection of free audio and video lectures that academic institutions post. There aren't too many in-depth CS lectures, but if you do a Power Search for "computer science" or something like that, you'll find some CS and CE topics.
If you don't mind a slightly more academic source, software-engineering radio ( http://www.se-radio.net/) is great.
About the time CUDA first came out, this series of lectures was made available on NVIDIA's web site.
What good technology podcasts are out there? is a similar, very popular question.
I tried some (mentioned here included), and with all due regret I must say that there are probably none worth listening. The lectures themselves are quite good, but the material is just not suited to the listening only - the lecturers keep referring to their whiteboard drawings, slides etc.
I can recommend the Berkeley course "Physics C10". The more informal name for it is Physics for future Presidents (PffP). It is both very informative and entertaining.
RSS feed for the latest installment, audio version: autumn 2009. It is in MP4 format; in earlier years it was in MP3 format.