[figomore]

Gnome Web is based on WebKit.

[layer8]

I should have added “cross-platform”. It’s not a viable alternative for most Firefox users.

[ranger_danger]

There are several, just none that are still maintained. But webkit is still open source and there's no reason someone could not fork or start up a new browser project with 90% of the work already done by webkit, you just need a GUI.