Chem4kids
Chem4 Kids: Lanthanide Series
This Chem4Kids site provides a general overview of the lanthanide and actinide series.
Other
Contributors to Discoveries of the Actinide Series
This page provides information about Stanley G. Thompson and Glenn T. Seaborg, both of whom contributed to the discovery of berkelium and californium of the actinide series. Very comprehensive site.
Other
Lanl: The Actinide Research Quarterly
This is "The Actinide Research Quarterly", a publication about current research of the actinide metals and nuclear materials technology by Los Alamos National Laboratory. Very detailed information.
Chem4kids
Chem4 Kids: Actinide Series of Metals
Take a look at the actinide series comprised of all radioactive elements on the periodic table.