New Rebrand Add-on Finally Available
Version 1.0 of my Rebrand Add-on is finally available.
The Rebrand add-on allows you to change the names and images that are used by Firefox and Thunderbird. You can change it to whatever you want. Here’s my browser:

Disclaimer: This extension is for entertainment purposes only. Do not try to ship your renamed browser. Also this add-on doesn’t fully rebrand on the Mac – the menubar name can’t be changed with an extension.
Enjoy!
OK, so I don’t know what you mean by the Mac menubar name, but I still wonder why you can’t change it.
I mean the name that appears in the upper left on a Mac next to the apple logo.
That name is not controlled by Firefox code, it’s controlled by the application bundle itself.
If I remember correctly, it can be changed by modifying CFBundleName in
/Applications/Firefox.app/Contents/Resources/en.lproj/InfoPlist.strings