Dictionaries

es-es

• Wiktionary
  • http://es.wiktionary.org

en-es/es-en

• WordReference
  • http://www.wordreference.com/
  • very good
  • with examples of usage
  • fast

• SpanishDict
  • http://www.spanishdict.com
  • with audio files for pronounciation
  • reasonably fast

• Freedict
  • http://www.freedict.com/onldict/spa.html
  • good for just looking up the meaning of a word
  • slow at times

Grammar

• Study Spanish
  • http://www.studyspanish.com/tutorial.htm
  • Free grammar tutorial
  • looks like a give away to promote the audio courses (non-free)