Here's a nice free one for Firefox to block out sites that distract you https://addons.mozilla.org/en-US/firefox/addon/4476 https://addons.mozilla.org/en-US/fir

Here's a nice free one for Firefox to block out sites that distract you https://addons.mozilla.org/en-US/firefox/addon/4476 https://addons.mozilla.org/en-US/firefox/addon/4476