Many activists in some countries are having their SSL connections intercepted by their own ISP's, under orders from their governments. I have been a bit of a political activist in the past in one of those countries. So man-in-the-middle attacks on my internet connections are a possibility. Unlikely, but possible. One strategy to counter mitm attacks is to tunnel through a free VPN. But in the path from the exit of the tunnel to the site being visited a man-in-the-middle scheme is still possible. Is it possible to connect to a site several times simultaneously through different free VPN tunnels, and only trust you are connecting to the right site if all the connections are identical in terms of the certificates they present? That would be a cool firefox addon.