Dictionaries, Encyclopedias & Digital Libraries

• Lexilogos
  Finnish-English Online Dictionary
• Forvo Pronunciation Dictionary
  Crowdsourced guide to pronunciation of Finnish words
• Kielitoimiston sanakirja 
  The definitive monolingual dictionary by the Institute for the Languages of Finland (Kotus)
• Wikisanakirja
  Finnish Wiktionary
• Dialectical Dictionary of Finnish
• Urbaani Sanakirja
  Finnish version of urban dictionary

Grammar

• Verbix Verb Conjugator
• The Language Gulper Introduction to Finnish
• Pronunciation of Finnish in a nutshell
  Guide to pronunciation of Finnish (for linguists)

Vocabulary

• Finnish words on Tumblr
  Word of the day with images
• Omniglot Useful Finnish Phrases
• WikiTravel 
  Finnish phrasebook
• SpeakFinnish!
  Modern, colloquial phrases for use across wide range of everyday situations
• My Best Helsinki
  Extensive list of food-related vocabulary

Reading & Writing

• Lingua
  Finnish Texts for Beginners

Listening & Speaking

• Radio Finland "Special Finnish"
  Daily five-minute broadcasts covering items of current interest. Language is simplified and slowed down. 
• inFinnish
  Audiobooks in Finnish

Online Course Materials

• Tavataan Taas!
  Introductory Finnish lessons
• Conversational Finnish course
  Transcripts of Finnish dialogues with idiomatic English translations
• Memrise Beginner's Finnish
  Introduction to the first few hundred words in Finnish
• Finnish 101
  Introductory Finnish lessons
• From Start to Finnish
  Short course including downloadable audio and vocabulary

News & Media

• Yle Uutiset
  Real News in Easy Finnish
• Random Finnish Lessons
  List of Finnish TV Shows (and where to watch)
• Yle Arena TV
  Finnish TV programs available for streaming abroad
• Ruutu
  Finnish TV programs available abroad

Social Media

• Learn Useless Finnish
  Facebook page dedicated to idiosyncracies and quirks of Finnish
• The Finnish Teacher
  Facebook page dedicated to the Finnish language

Arts, Films & Music

• Yle Puhe
  Collection of radio programs in Finnish (for advanced listening)
• Radio Suomipop
  Finnish pop radio
• Final Appearance
  Story in Finnish and translated into English
• The Weight of Words
  Story in Finnish and translated into English