[hbn]

Does that ever work in practice? Has there been a standard fork of Audacity that everyone flocked to since they got purchased by Muse?

[capableweb]

Tons of example. Most wildly used forks out there are probably WebKit and Blink, the engines of two popular browsers.

Some other notable projects that started as forks: postgres, Wordpress, Apache Server, OpenSSH. I'm sure there are others I forgot.