This came off of http://www.futureproducers.com/
these might not be the greatest, but some make for a good starting point
Free Audio Software:
1) Audacity (http://audacity.sourceforge.net/)
Audacity is a free audio editor. You can record sounds, play sounds, import and export WAV, AIFF, Ogg Vorbis, and MP3 files, and more. Use it to edit your sounds using Cut, Copy and Paste (with unlimited Undo), mix tracks together, or apply effects to your recordings. It also has a built-in amplitude envelope editor, a customizable spectrogram mode and a frequency analysis window for audio analysis applications. Built-in effects include Echo, Change Tempo, and Noise Removal, and it also supports VST and LADSPA plug-in effects.
2) Muse (http://muse.serverkommune.de/)
MusE is a MIDI/Audio sequencer with recording and editing capabilities written by Werner Schweer. MusE aims to be a complete multitrack virtual studio for Linux, it is published under the GNU General Public License.
3) Ardour (http://www.ardour.org./), suggested by Homershines
Ardour is a digital audio workstation. You can use it to record, edit and mix multi-track audio. Produce your own CD's. Mix video soundtracks. Experiment with new ideas about music and sound. Ardour capabilities include: multichannel recording, non-linear, non-destructive region based editing with unlimited undo/redo, full automation support, a mixer whose capabilities rival high end hardware consoles, lots of plugins to warp, shift and shape your music, and controllable from hardware control surfaces at the same time as it syncs to timecode. If you've been looking for a tool similar to ProTools, Nuendo, Cubase SX or Sequoia, you might have found it. (available for Linux, MAC port appears to be in progress)
4) Rosegarden (http://www.rosegardenmusic.com/), suggested by Homershines
Rosegarden is a professional audio and MIDI sequencer, score editor, and general-purpose music composition and editing environment. Rosegarden is an easy-to-learn, attractive application that runs on Linux, ideal for composers, musicians, music students, and small studio or home recording environments.
Plogue's Bidule
http://www.plogue.com/
Ardour
www.ardour.org.
Rosegarden
http://www.rosegardenmusic.com/