Hyper history Online
http://www.hyperhistory.com/online_n2/History_n2/a.html
Presents 3,000 years of world history with an interactive combination of lifelines, timelines, and maps. Endorsed by the History Channel and Discovery Channel.

InfoPlease.com
<http://www.infoplease.com/yearbyyear.html>
The 20th Century year by year with key events listed. Also covers first part of 21st century.

KidsClick
http://www.kidsclick.org/
KidsClick is a site maintained by librarians offering web sites for kids grades K-7 on a wide variety of education and home schooling topics. Links to resources for home schooling parents too. Over 600 subjects, including history.