Gadolinium is the best neutron absorber and is used in nuclear reactors. Terbium is used in green lasers. Dysprosium absorbs neutrons and is used to control nuclear reactors. Holmium is used in color phosphors. Erbium is used in color phopsphors.
Thulium is used in color phosphors.
Ytterbium is used in color phosphors. Lutetium is used in color phosphors. Hafnium absorbs neutrons and is used to control nuclear reactors. Tantalum doesn't corrode and is used in artificial knee and hip replacements. Rhenium is rare and is used in special light bulb filiments.