Sources for the various background music files:

[silence.ogg]
Generated 2 secs of silence - dd if=/dev/zero of=silence.pcm bs=176400 count=2 ; oggenc -r silence.pcm
Generated by Neil Muller, Aug 2010
Not copyrightable.

[MTA.ogg]
Kevin MacLeod (incompetech.com)
Licensed under Creative Commons "Attribution 3.0" http://creativecommons.org/licenses/by/3.0/
Ogg produced via: mplayer -ao pcm:file=MTA.wav MTA.mp3 ; oggenc -q 1 MTA.wav

[shiny_tech.ogg]
Kevin MacLeod (incompetech.com)
Licensed under Creative Commons "Attribution 3.0" http://creativecommons.org/licenses/by/3.0/
Ogg produced via: mplayer -ao pcm:file=shiny_tech.wav "Shiny Tech.mp3" ; oggenc -q 1 shiny_tech.wav

[phat_sketch.ogg]
Kevin MacLeod http://freepd.com/Unclassified%20Electronic/Phat%20Sketch
Public Domain
Ogg produced via: mplayer -ao pcm:file=test.wav "Phat Sketch.mp3" ; sox test.wav phat_sketch.wav vol 0.35 ; oggenc -q 1 phat_sketch.wav

[electronic_k_deep_nyah.ogg]
Frank Nora http://freepd.com/Unclassified%20Electronic/Electronic%20K%20Deep%20Nyah
Public Domain
Ogg produced via: mplayer "Electronic K Deep Nyah.mp3" -ao pcm:file=electronic_k_deep_nyah.wav ; oggenc -q 1 electronic_k_deep_nyah.wav

[electronic_u_popper.ogg]
Frank Nora http://freepd.com/Unclassified%20Electronic/Electronic%20U%20Popper
Public Domain
Ogg produced via: mplayer -ao pcm:file=test.wav "Electronic U Popper.mp3" ; sox test.wav electronic_u_popper.wav vol 0.75; oggenc -q 1 electronic_u_popper.wav