energyXT
http://www.energy-xt.com
All-in-one synthesizer, sampler, drum machine, multi-fx procesor, mixer and MIDI/audio sequencer with audio recording, freeze, time-stretching and pitch-shifting for Windows, MacOSX and Linux.
Download now, launch and create music in no time! License is 59 euro only, for a complete music studio on your PC or laptop.
Qtractor
http://qtractor.sourceforge.net/
Qtractor is an Audio/MIDI multi-track sequencer application written in C++ with the Qt4 framework. Target platform is Linux, where the Jack Audio Connection Kit (JACK) for audio, and the Advanced Linux Sound Architecture (ALSA) for MIDI.
Qtractor is free, open-source software, distributed under the terms of the GNU General Public License (GPL) version 2 or later.
Indamixx
http://www.indamixx.com/
Finally you can take your studio with you! Ideal for Producers, Remixers, and DJs on the go!