www.picture-history.com

This is a very cool site. They have images from the last 150 years and arranged by collection. Some of the collections include:

• African Americans
• Civil War
• Europe
• Indians
• United States in the 1930s and 1940s
• Old West

What I like most about this site, however, is the quality of the images. They are just amazing. I'm already trying to find some to use later on this semester with my lectures.