It is used in thermometers. Thallium is a very soft metal. It is toxic and was used in rat poison. Bismuth has a low melting point. Automatic fire sprinklers have a plug of bismuth which melts when it gets too hot.
Polonium is used in special anti-static brushes.
Radon is a gas used in radiation therapy for cancer. Radium is used in luminous paint. Actinium is used as a source of neutrons. Thorium is used in the glowing mantles in gas lanterns. Protactinium is very rare and has few uses.