Ardour: ardour.org
JAMin: jamin.sourceforge.net
LADSPA: www.ladspa.org, plugin.org.uk (Steve Harris's collection) and tap-plugins.sourceforge.net (a collection from Tom Szilagyi)
ALSA: www.alsa-project.org
Rosegarden: www.rosegardenmusic.com
Quick Toots Series: www.djcj.org
Audio-optimized Linux distributions and packages:
AGNULA (Debian): www.agnula.org
Planet CCRMA (Red Hat/Fedora): ccrma.stanford.edu/planetccrma/software
AudioSlack (SlackWare): www.audioslack.com
Thac's RPMs (Mandrake): rpm.nyvalls.se
SuSE (not necessarily audio-optimized, but has good out-of-box audio support): www.suse.com/us/index.html
Listen to the original song recorded for this article on the author's site at: linux-sound.org/ardour-music.html