Disclosure -- I create content for Pavlok. :)
First off, huge shoutout to all the other awesome tools on the list. I'm a huge fan of OneTab myself.
That being said, the Pavlok Chrome extension is incredible for helping you stay focused and reduced the amount of distracting open tabs.
The extension allows you to set your desired tab amount (say I would like no more than 7 tabs for example), and if you open more you'll be greeted with a nice, shock/beep/or vibration. Your choice.
It even has the option to give you a warning if you're getting close to your limit, which is huge for creating awarness.
After months of using it relgiously, I am MUCH more aware of my tab usage. :)