HTTPS Everywhere is an add-on for Firefox that automatically converts HTTP to HTTPS for the following sites:
- DuckDuckGo
- EFF
- GentooBugzilla
- Google Search
- Google Services
- Identica
- Ixquick
- Mozilla
- Noisebridge
- NYTimes
- PayPal
- Scroogle
- Torproject
- WashingtonPost
- Wikipedia
How to use:
Just install the add-on and it will automatically start working. You can also select the sites to enable/disable in its options window: