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.
University of California
Ucmp: Web Geological Time Machine
The Museum of Paleontology at Berkeley offers an online geological time machine which allows you to catch a glimpse of ancient eras in earth's history. Click into an "Era" to learn about its stratigraphy, life forms, localities, and...
Other
Georgia Perimeter College: The Precambrian Era
This resource provides detailed information on each of the periods within the Precambrian Era. It discusses what earth was like, what the first multiple cell organisms were like and when they appeared.