Ctrl + L gives you the option to link the modifiers from the active object to all other selected objects.

This will overwrite the modifiers of the object being copied to, so there is a really useful plugin to copy any one of the modifiers and not overwrite others, which is called: 3D View: Copy Attributes Menu.

When this is enabled, use the hotkey Crtl+c to bring up the menu options, and use the copy selected modifiers option to copy your modifier.

Ctrl+L gives you the option to link the modifiers from the active object to all other selected objects.

This will overwrite the modifiers of the object being copied to, so there is a really useful plugin to copy any one of the modifiers and not overwrite others, which is called: 3D View: Copy Attributes Menu.

When this is enabled, use the hotkey Crtl+C to bring up the menu options, and use the copy selected modifiers option to copy your modifier.