YouTube is a website that has a vast and diverse library of videos. It can be used for research or entertainment and is full of interesting and funny content.
Amazon might be my favorite website. It provides the single most convenient way to buy nearly anything directly from your home, and usually has good deals.
Wikipedia is an online encyclopedia with a plethora of information that is completely free to access, and can be contributed to by anyone. While a simple google search may give you a surface level answer to your search, finding an article for that same search will give you a much deeper look.
As a bass player, ultimate guitar helps me find musical notation for songs that I like, and allows me to learn them. It has music for guitar, bass, ukelele and more.
Instagram is one of the most popular social media platforms and has direct messaging for you and your friends, pictures, both artistic and fun, and is also a resource for memes.
When I was younger, I used to spend hours on Miniclip. They have many free games for kids to play.
IGN is a news source for video games, comics and sci-fi/fantasy movies and telivison programs. They also make walkthroughs for video games.
I am a huge comic book fan, and Marvel's website has a feature called Marvel Unlimited that, for a small monthly fee, allows you to read thousands of comics from your computer or phone. They also have games and updates on their comics, movies, shows, and video games.