CUETools - CUETools is a suite of tools for converting and verifying lossless CD rips.
MixPad - MixPad is free music Music Mixer and Recording software designed for easy audio production.
Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
Add Audio to Video - Add Audio to Video empowers you to add custom audio tracks to your video files.
FL Studio - Image-Line's FL Studio, now on it's 12th version, is a well-known music production suite and the most popular beat processor on the market, due no doubt to its longevity. Read more about FL Studio.
Audio Video Editor and Mixer - Audio Video Editor and Mixer is a tool that helps you add changes to your video and audio files.