Recording -

Audacity - http://audacity.sourceforge.net/
Podcasts
Speech-to-text conversion - Dragon Naturally Speaking is effective with training, a powerful computer, a compatible recorder and a good microphone.

Converting information into audio performance requires synthesis.

Content delivery and assessment for aural learners - provide podcasts and audio recordings available on the web as substitute for text.

http://mp3.radified.com/
http://www.chrismyden.com/bestmp3guide.php
http://mp3.about.com/od/musiclibrarymaintenance/tp/top_mp3_tasks.htm
http://howto.wired.com/wiki/Get_Rid_of_Your_CDs_and_DVDs