Reading

Dictionary/Flashcards

Nciku

MDBG

Yellowbridge (dictionary, etymology, flashcards)

海词-Dict.cn

CNKI

Youdao

iCIBA

The Classical Chinese Dictionary (文言文字典)

Anki (flashcards)

Videos/Movies/Television

Podcasts/Video Lessons

Mobile Apps

Hanping (Dictionary)

Pleco (Dictionary)

海词-Dict.cn (Dictionary)

网易-NetEase (News)

新浪新闻- Sina (News)

Tunein (live radio)

Cbox (live television, movies, etc…)

Skritter (character practice)

Hanzicraft (character practice)

Chinese Writer (stroke order practice)

Google IME  (Chinese writing input for Android)

Hanzireader (reading annotator-iOS only)

Chinese Word Puzzle HD (crossword game)

Miscellaneous

Tunein (live radio)

Justing (audiobooks)

Sharedtalk (language exchange, chat)

Italki (language exchange, chat, online tutoring)

Lang-8 (language exchange, writing practice/editing)

Mandarin Spot (reading annotator)

Marco Polo Project (translation practice)

Ninchanese.com (language learning software, multiplayer Chinese vocabulary games)

The Washington Chinese Language Meetup Group

Learn Chinese ABC (pronunciation)

Praat (tones/pronunciation, voice recording software) 

Audacity (tones/pronunciation, voice recording software) 

Blogs/Newsletters

Sinocism (News/Policy in English and Chinese)

Hacking Chinese (Language learning, acquisition, maintenance)