Find easy, free and powerful music editor is not so simple. Take a look on AudioMass.
This is autotranslated version of this post.
AudioMass will help you to record audio or to edit the current track using high-grade tools cut, copy, effects, distortion and more.
At first glance, the service looks very simple. However, it's almost a professional tool to work with audio. It supports hotkeys, so you can easily manage all the tools of the edit.