JonDoFox contains the add-on HTTPSEverywhere. It redirects the traffic to more than 1,000 websites to the HTTPS encrypted version.
If you want to enforce HTTPS encryption to more wensites you may add the domain to the list of HTTPS only websites in NoScript or you may write own rules for HTTPSEverywhere. NoScript can only rewrite http:// with https://. With new rules for HTTPSEverywhere it is possible to implement complex URL rewriting.
NoScript lets you conveniently enforce HTTPS on your connections. Right-click on the NoScript icon . In the Options -> Advanced -> HTTPS -> Behavior panel NoScript offers the opportunity to build a whitelist as seen in the following screenshot. You may specify single domains and/or an arbitrary amount of subdomains using a wildcard symbol.