The Internet offers a lot of great timelines that are invaluable for teaching history and seeing connections.  They are also a great tool to help students create their own connections and make illustrated timelines.

AlternaTime
Huge timeline collection

American Educational History Timeline

Department of Agriculture Timeline of Growth
From the Cato Institute

Education – Timeline Index
Massive timeline collection

Explorers’ Timeline

Food Timeline

Holocaust Timeline

HyperHistory Online
This excellent, visually appealing timeline includes science, culture, religion and politics.

K-12 Timelines

Lewis and Clark Timelines

Maps, Flags, Timelines
Major timeline links

Math History Timeline

Time Line Maker

Timeline Archive – Infoplease.com
All subject areas

Timeline Index
Who, what, when, where timelines 

Timeline of Computer History

Timelines of History

Timelines of Invention and Technology

Timelines.com
History timelines with photos

World Timeline
Goes back to prehistoric times