I’ve got very used to gestures in Mozilla courtesy of the optimoz project. They’ve now released a preview of pie menus for Mozilla.
The RadialContext menu is a hierarchical, context-sensitive pie menu for Mozilla. It offers an alternative to both the normal context menu and
mouse gestures. The feeling is very similar to mouse gestures. But there also is a GUI so you don’t have to look up what options are available in the given
context.
More about Pie Menus at piemenus.com, in this slashdot thread, at nooface, and here.