Audio Hijack!

Audacity is free, open source software for recording and editing sounds. You can use Audacity to record live audio, convert tapes and records, edit sound files, change the speed or pitch of a recording and much more.

Sound Siphon is a software package that makes your Mac’s audio output available as an audio input device. It enables you to send audio from one application to another where it can be processed, streamed, or recorded.

Total Recorder is a multi-purpose audio and video recording software program with a wide variety of editing and sound processing capabilities. Total Recorder is distributed in the following editions: Standard Edition (SE), Professional Edition (PE), VideoPro Edition (VE), and Developer Edition (DE). VideoPro Edition and Developer Edition are powerful tools for recording, editing, converting, and playing sound and video files. Standard Edition and Professional Edition are all-in-one audio solutions designed to meet all of your needs for working with audio. »

Piezo makes it a snap to record audio on your Mac. With just a few clicks, you can record audio from any application, or from audio input devices like microphones. Piezo's great for recording from VoIP applications like Skype and iChat as well. Save conversations or interviews for podcasts.

AudioDroid : Audio Mix Studio is a sound & music recorder, editor and mixer. You can edit and mix MP3, MP4, WAV, AAC, OGG and AMR audio files and create ringtones, alarms, and notifications from them. AudioDroid allows you to add new tracks, mix the tracks and save the mixed audio file in mp3 format. You can record audio with your device microphone and mix the recorded audio file with other audio tracks. Just import your instrumental and then record your voice over it. You can make time shift on audio files and crop them. »

Callnote Premium is a Free application that allows to record Skype, Google+ Hangouts, FaceTime, Viber, Facebook, GoToMeeting and WebEx Audio and Video Calls. You can also make instant video snapshots along the way. You can whether record the entire call or start/stop whenever you need. Manage your recording library right on your computer, store your conversations in Evernote or Dropbox, share videos on Facebook or even post it to Youtube. Save participant names, call time and duration for future reference with Callnote Premium Video and Audio call recorder. Callnote Premium allows to record up to 30 video and audio calls absolutely free with no payment information asked. Application supports following languages: English, Spanish, German, Russian, French and Japanese. »

Audion is a light, simple and powerful audio CDs and MP3s player.

As a professional real-time audio recording and editing software, Boilsoft Audio Recorder can record lossless sounds from any internal or external sources such as Microphone, CD player, line-in devices and other applications (like Skype, QuickTime Player, RealPlayer, iTunes, VLC, or DVD Player) into any popular audio format including MP3, WAV, AIFF, AAC, AC3, AU, FLAC, M4A, M4R, MATROSK and OGG.