Excellent collection of tools appropriate for Intermediate and Advanced Spanish learners focusing on writing, grammar & language structure. This webpage can also be useful to eager Beginner Spanish learners.
Authentic Puerto Rican Spanish website with multiple resources appropriate for all Spanish learners. It is aimed to help students complete their school assignments at home. The Spanish section has everything from language structure and grammar to stories, poems, news, etc. The other content areas can be used for the ACTFL's Connection standard.
Online textbook for beginning Spanish courses that covers all of the major grammar rules, moving slowly and offering exercises and plenty of examples as well as vocabulary and phrases.
Spanish Proficiency Exercises is a compilation of brief video clips in which native speakers of Spanish from various locations throughout Latin America and Spain demonstrate various language tasks. The site incorporates proficiency topics, divided by level of dificulty: Beginning, Intermediate, Advanced, Superior. The specific topics include video clips, vocabulary lists, phrases lists, and mini-grammar explanations.
Learn Spanish online. You can follow the course or search for a particular lesson. Useful for all levels. It also has a "Resources" section with downloadable lessons on verbs, adjectives, pronouns, nouns, etc.