Focusbook for Chrome
More About Focusbook
Focusbook helps you stay productive on Facebook. When you first open it, it will demand that you specify a goal, and it will remind of that goal periodically, until you close Facebook.
It's not well built by any standard and has some bugs. But I'm finding that these annoying bugs actually make it MORE effective, so I might leave them for now.
DEVS - pull requests welcome: https://github.com/yonahforst/focusbook
added 'safe for work' mode