Diccionario de la Lengua Española
http://buscon.rae.es/draeI/
The official online dictionary of the Real Academia Española.

Latin American Network Information Center (LANIC)
http://lanic.utexas.edu/las.html
LANIC serves as a resource guide for information to, from and on Latin America. Browse by subject area, by country, or search the Web site by keyword. Many of the resources linked are available in Spanish. Maintained by University of Texas at Austin.

Red de Revistas Cientificas de America Latina y el Caribe, España y Portugal (RedAlyc)
http://redalyc.uaemex.mx/
Network of Scientific Journals of Latin America, the Caribbean, Spain and Portugal ( RedAlyc) is an open access portal supported by the Universidad Autónoma del Estado de México. It provides access to over 300 journals and more than 60,000 freely available full text articles.  RedAlyc covers subjects in the humanities and social sciences.