University of California
Ucmp: Divisions of Precambrian Time
This site provides a brief overview of the Precambrian Era and provides a clickable chart that breaks down this era into five different time frames. A lot of info is provided on each of the five.
The Field Museum
Field Museum: Exhibits: Evolving Planet: Precambrian
This interesting tour examines how life began on earth, provides images of the first life forms, and delves into the role that photosynthesis sexual reproduction, and natural selection played in the the Precambrian period. Listen to...