Learn vocabulary and feed the hungry. Freerice.com is a vocabulary quiz site. For every right answer you select, they give 10 grains of rice to the hungry. Get all the way to level 60 and learn what anergy, mammock, and solation mean.
Explore the world and test your geography knowledge at the same time. GeoGuessr is a game where you guess the location of a picture using a world map. The closer you are to the location, the more points you get. At the end of five rounds you find out your total score.
Every time you load the website, you get a new song and a new cat gif. Cats and music, what else do you need?
Reddit is possibly the most addicting website on the Internet. Reddit is a community of people with specific subreddits on pretty much everything. Whether it be science, gaming, starcraft, or birds with arms, Reddit has it. If it exists, there is a subreddit for it.
Confused about what is a truth and what is a lie? Snopes.com has you covered. Find out if the claims that shady politician is making are true, or if the story you mom always told you is an old wives’ tale.
With stumbleupon.com you will reach parts of the Internet you did not know existed. Select your interests, and Stumble Upon will send you all over the web with websites and articles that might interest you.
Similarly to stumbleupon.com, theuselessweb.com takes you to a random website with one click. The only difference is that these websites are completely useless. Need a random color? They have it covered. Is you name Dan? Hear the beautiful sound of your name. Do you like Breaking Bad or the sound a bell makes? Ding!
Everyone knows cool guys walk away from explosions, especially tvtropes.org. Learn every movie/television cliché and trend and when it happened.
The ultimate source for time wasting. Learn about anything and everything. Wikipedia has well-cited articles on almost anything you can think of. Need a place to start? Try the list of common misconceptions, the list of unusual articles, or the list of lists of lists.
Bonus: Check out f*ckinghomepage.com for daily interesting web links.