Some (very) good ambient music which can be downloaded for free:
“Hope’s not lost” by various artists:
http://www.ambientmusicblog.com/2010/07/22/hopes-not-lost-by-various-artists/
Some good ambient drone music:
http://www.ambientmusicblog.com/2010/07/22/music-for-bathyscaphes/
Nobuto Suda from Tokyo, Japan made a nice 20-minute ambient track. It can be downloaded for free here: http://ruralcolours.co.uk/news/?page_id=44%22
Hibernate Recordings released the Hibernate Sampler 2. You can download it for free after entering your e-mail address or you can donate something here:
http://hibernaterecordings.bandcamp.com/album/hibernate-sampler-volume-2
Enjoy!
