The FSI Languages Courses Free Language Learning were developed by the U.S. Government and are now freely available in the public domain. There are 73 language learning courses here.
All content on the site is organised into units, and each tape in each unit contains an MP3 file. You can follow along with the audio tapes using the accompanying PDF files, and some units also include exercise manuals.
Languages you can learn: French, Spanish, Arabic, German, Italian, Korean, Cambodian, Japanese, Portuguese, Amharic, Arabic, Bengali and more