Automated Website Viewer in Browser

I'm looking to get my web browser (Mozilla Firefox) to automatically load websites, one after another. I'm not quite sure the best way to do this. I'm looking for ideas. It must be scalable, because it will be dealing with 10,000's of URLs. >> Please PMB me how you will do it. << (The use of windows automation programs are also a possibility, if it can't be done purely by inbrowser scripting.)