Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
Keezy Drummer - Make a beat in seconds
Oceanaudio - Ocenaudio is a cross-platform, easy to use, fast and functional audio editor.
Sampulator - Make (and record) beats on your keyboard
GoldWave - GoldWave. Digital Audio Editing Software. Record • Restore • Convert • Analyze. Fully loaded to do everything from the simplest recording and editing to the most sophisticated audio processing, restoration, enhancements, analysis, and conversions.
Auxy Music Studio - Auxy brings real music creation to iPhone in a simple and inspiring format.