The Gilder Lehrman Institute of American History's quarterly online journal put together a fantastic issue on nineteenth century technology a few years ago. Five short, informative thematic essays by knowledgeable authorities on the period are supplemented with a wonderful resources section of web links for the study of nineteenth century innovation and inventors.
The University of Virginia hosts a series of great pages on the 1893 Columbian Exposition in Chicago that can give you a real sense not only of why it was such a huge cultural event, but also what it was actually like to attend.
The technology themed section of the PBS American Experience archive is the gateway to the transcripts of several great documentaries and includes resource pages for each film. There's a surprising wealth of information—written by recognized historians—and links to some pretty cool primary documents like the entire list of Thomas Edison's U.S. patents.
There's also an "Innovators" section on PBS's "Who Made America" website that features biographical sketches of dozens of American inventors, links to articles their work and context, and a time line laying it all out chronologically.
The Massachusetts Institute of Technology maintains a fairly similar page with lots of information and resources for studying the history of science, technology, and innovation.