Stylish, a popular extension available for Chrome and Firefox which allows for easy customization of any website, now phones home and shares its users' browser history with its corporate parent, according to blogger Robert Heaton. This prompted Firefox to ban the extension from its addons site and prompt all users to disable it. The discussion can be seen in the relevant bug report. In Heaton's words:

Stylish is no longer a well-meaning product with your best interests at heart. If you use and like Stylish, please uninstall it and switch to an alternative like Stylus, an offshoot from the good old version of Stylish that works in much the same way, minus the spyware.