Just tried Toucan and it can't be disabled on localhost, a major pain for using it during work as an engineer. For those that haven't used toucan, it's an extension that translates words/phrases inline on a page with various levels of replacement frequency and complexity based on your proficiency with the language.
Nice idea - although I hate having to start from scratch and having to "train" the system to know my level and vocabulary. I think it's a bummer that it's not common to be be able to exchange vocabulary lists between apps.