There are some excellent sources out on the Web; there are also some that are of varying quality. Even though Web resources are free, I'd suggest being as careful in selecting Web sites as you would be about choosing resources you would buy.
When I search the Web for course-related resources, my first stop is usually one of the sources listed as Subject Guides by the Tool Kit for the Expert Web Searcher from the Library and Information Technology Association. I particularly like the Internet Scout. I also use INFOMINE from the UC system.
Several search tools, including Alta Vista, Google, and Yahoo will let you search for sites from certain domains, which can be very useful.
As a test case for Web quality, you might want to look at this site, Main Causes of the Great Depression. This site, or something like it, might be interesting to use as an example for evaluation skills.
Another interesting test is to try the same search in several different search engines, just to get a feel for what you might find.
Our examples: Ask Jeeves, Alta Vista, and Google.
Searching the Web: Selected Links
For your browsing enjoyment, this is a list of a number of links on eras of American history, history in general, teaching resources, and more for Historical Research on the Internet , Lawrence University Summer Institute