Here’s a list of the most popular websites which, at the moment, are blocked in China:
Facebook, Twitter, Instagram, Pinterest, Tumblr, Snapchat, Picasa, WordPress.com, Blogspot, Blogger, Flickr, SoundCloud, Google+, Google Hangouts, Hootsuite.
Google Play (this means that without a VPN you won’t be able to download any apps from Google Play), Line, KaKao Talk, Telegram.
Google (both Google.com and the majority of local versions like Google.com.hk, Google.fr, etcetera), Duck Duck Go, various foreign versions of Baidu and Yahoo.
The New York Times, Finacial Times, The Wall Street Journal, The Economist Bloomberg, Reuters, LeMonde, L’Equipe (What do they have against the French?), Netflix, Youtube, Vimeo, Google News, Daily Motion, many pages of Wikipedia, Wikileaks.
Google Drive, Google Docs, Gmail, Google Calendar (generally all Google services), Dropbox, ShutterStock, iStockPhotos, WayBackMachine, Scribd, Xing, Android, and many VPN sites.