Title says it all !
I used to have a kinda boring routine when I was still playing wow in high school ( mainly wow forum/mmoc patchnotes/ facebook).
But it largely improved in recent years and I'm discovering really interesting stuff that i wish I knew about earlier.
Most useful:
Wikiwand, basically a prettier and customizable wikipedia layout (content is the same). Really an improvement from the aggressively white default page.
Brilliant, fun and engaging ways to approach math and physics concepts.
Wolfram Alpha Search engine for...basically everything. It directly attempts to pull out data rather than displaying links. You can make request about just anything and it can decompose complex equations to suggest step by step solution or generate new problems.
Favorites:
Hackaday Nothing to do with balaclava wearing russians in front of green CMDs, it is more of an hardware oriented site. It is very informative if you like making/electronics and most people there have great wits.
RationalWiki, Humorous wiki about debunking wingnuts and crank theories. Hilarious and dangerously addictive
Here you go, your turn to give us your best links. Maybe you'll change someone's browsing habits !
(Please don't post porn)