Some parts of my web site have been configured to use the HTTPS protocol, with 256-bit encryption by a certificate you can get for free at
http://www.startssl.com/, a Certificate Authority which is recognized by about any browser, except Internet Exploder and Opera. However, unfortunately they now use a Class 1 Intermediate Server CA for these certificates, and this Intermediate CA isn't installed (yet) in these browsers (and you have to get the Root CA for Internet Exploder and Opera also anyway, because they don't recognize StartSSL at all)...
To install this Intermediate CA, go here for the CRT file and here for the PEM file. For Internet Exploder and Opera, first click here to retrieve the Root CA (and if that doesn't work, click here to retrieve the PEM file instead), then get the Intermediate CA on the left. Then all your troubles will go away and you can live happily ever after.
