It works under all Operating Systems, but it's interesting especially for Linux.
The Flash plugin for Linux has a painful bug, all Flash content is always covering the other elements of the page, hiding and making inaccessible other parts of the page like dropdown menus, preventing to navigate on these sites. Flash Killer remove them with one click!
Flash Killer add an item to the contextual menu, as well as an item in the Tools menu. You can remove these items in the options if you prefer.
A button is available too for your toolbar. Right click on the toolbar, choose 'Customize...', drag and drop the 'Flash Killer' button.
How to put back the Flash contents?
Just reload the current page ;) .
If you desire a more radical extension, to block all Flash contents as soon as a page is loading, take a look at the FlashBlock extension.
The PrefBar extension contains too a button to eliminate the Flash, so if you use it, Flash Killer is useless.