[MasterScrat]

A similar idea that comes to mind seeing this:

Every hour, you should see a quick summary of the pages you browsed through for the past hour.

It's easy to waste time not realizing how long you spent on AskReddit/TvTropes/whatever...

But if an hour of browsing flashes before your eyes and you can see nothing productive, it will wake you up.

[halflings]

This doesn't look super pretty, but seems to do the job:

https://chrome.google.com/webstore/detail/timestats/ejifodhj...

[946789987649]

I really like that, I might get to work on it. Can't imagine it'd be too hard.