Rated 5 out of 5 stars

Good job. I wonder why nobody implemented this sooner!

Feature request: let the user select from a preset popular (e.g. IE6 on Windows, Safari on iPhone, ...) or special (e.g. GoogleBot!) user agents.

Another (crazy!) feature request for best privacy: support random UA generation, and maybe let the user define the template or set some parameters. For example user want to give www.google.com a random UA each time using the template: {Firefox,Chrome,IE,Safari} on {Ubuntu,Gentoo,Arch,XP,Vista,7,MacOS} + some randomized version numbers for Flash, Java plugin, .NET plugin, etc.

This review is for a previous version of the add-on (0.0.5).