Rated 4 out of 5 stars
1. Does MD5 Reborned Hasher 0.9.0 extension (add-on) work with Firefox 11.0 on Windows 7 Ultimate x64?
2. Is this the only MD5 Checksum add-on for Firefox 11.0? If no, what are the other ones, and which one is the best?
1. Yes! It works on Windows 7 Ultimate x64 (it's what I use).
2. It isn't the only one but you can use complement search page to find more and test other to see what is better. https://addons.mozilla.org/es-ES/firefox/search/?q=md5