Dictionaries, Encyclopedias & Digital Libraries

• Lexilogos
  List of Polish dictionaries
• Polish Dictionary
  Dictionary with brief modules on vocabulary and grammar.
• Polish-English Dictionary
  Bilingual dictionary developed at the University of Pittsburgh 
• Lingvopedia
  Colorful overview of Polish language

Grammar

• Polish Grammar
• Extensive Guide to Polish Grammar
• A course in Polish language (with a focus on grammar)

Vocabulary

• Polish vocabulary lessons on YouTube
  A series of vocabulary words in Polish presented through photos, script and audio.
• Language Guide
  Basic vocabulary presented as images and sound files

Reading & Writing

• Omniglot
  Introduction to reading and writing in polish
• Polish literature
  Links to Polish literature in both Polish and English

Listening & Speaking

• PolishPod101
  Listening Comprehension for Absolute Beginners

Online Course Materials

• Polish 101 on Youtube
  Online video-based Polish course, focusing on introductory conversations and basic vocabulary.
• Foreign Service Institute Polish course
  Downloadable language learning manuals
• Learn Polish
  Basics of Polish language with links to quizzes and reference materials
• Mówić Po Polsku
  An introduction to Polish

News & Media

• Polskie Radio
• Polish language newspapers
• Gazeta
• Polishnews.com

Arts, Films & Music

• Artyzm
  Comprehensive online guide to Polish artists and galleries
• Virtual Library of Polish Literature
• Kinoeye
  An article on Polish cinema
• Wikipedia
  Information about Poland