i run firefox (and love it). i just installed this and so far so good. we'll see
The Electronic Frontier Foundation and The Onion Router (TOR) project have teamed up to release a new privacy-enhancing Firefox plugin called HTTPS Everywhere. It was inspired by Google's new encrypted search engine, and it ensures that whenever you visit a site that accepts encrypted connections, your browser switches into encrypted mode, hiding your traffic from snoops on your local network and at your ISP. HTTPS Everywhere covers Google search, Wikipedia, Twitter, Identi.ca, Facebook, EFF, Tor, Scroogle, DuckDuckGo, Ixquick and other smaller search engines. It's still in beta (what isn't?) but I've been running it all morning with no negative side effects.
Encrypt the Web with the HTTPS Everywhere Firefox Extension (Thanks, Hugh!)