Diccionarios

Spanish-English Dictionaries

• http://education.yahoo.com/reference/dict_en_es/ - This is a straightforward Spanish-English dictionary.
  
• http://www.wordreference.com/ - This is a handy all-purpose site, with Spanish-Spanish and Spanish-English lookup. The most unique and useful feature of wordreference are the forums, where you can read people's questions and answers about words and phrases -- this is especially useful for learning about slang.
  

Spanish Dictionaries

These dictionaries are only Spanish-Spanish.

• Real Academia - This is the dictionary created by the "Real Academia Española" (The Royal Spanish Academy). It is the most thorough dictionary of Spanish in existence, and is freely available online. It is highly unlikely that a word you are looking for cannot be found in this dictioanry.
• http://www.wordreference.com/ - This is a handy all-purpose site, with Spanish-Spanish and Spanish-English lookup. The most unique and useful feature of wordreference are the forums, where you can read people's questions and answers about words and phrases -- this is especially useful for learning about slang.

Grammar

Grammar Guide

Mr. Hinkle's grammar book (a draft in-progress) is available online for you to use: Spanish is Not English: A Brief Guide to Spanish Grammar: Grammar Guide.

Other Handouts

Preterit and Present basic forms review sheet
Reflexive Verbs Review & Homework