WavTap for Mac records all sound that's coming from your computer and saves it in a WAV file on your desktop. It's an extremely basic app that resides in your Mac menu bar and has no configuration options. In addition to the record functionality, there is also a handy buffer that stores the last 20 seconds worth of audio in case you couldn't start recording in time.
Following a straightforward installation, which requires an administrative password, WavTap for Mac places a small wave icon on the menu bar. You can begin recording by using either the menu or a keyboard shortcut. When the recording is stopped, a WAV file will appear on the desktop. In our tests we were able to successfully record 15 minutes of audio without experiencing performance issues. WavTap for Mac also features a buffer that stores the sound for the last 20 seconds, which can be exported only via the drop-down menu; there is no shortcut for this option.
If you want to record a VoIP conversation, or if you need to document abnormal behavior in an app, WavTap for Mac offers a great, free way to save all audio generated by the system and apps. Despite being extremely basic and focused, it can be useful, so do check it out.