Lanthanum is a lanthanoid with many uses. Nickel-metal hydride batteries require lanthanum in their production.
Molycorp - http://www.molycorp.com/products/cerium.html - Molycorp is a mining and marketing subsidiary of Chevron (NYSE: CVX) that produces lanthanum and other lanthanides.
Metall Rare Earth Limited - http://www.metall.com.cn/la.htm Great Western Minerals Group (CVE: GWG)
Neo Material Technologies (TSE: NEM)
Avalon Rare Metals (TSE: AVL)