Real Academia EspañolaContains an online version of the 22nd ed. of the Diccionario de la Lengua Española. Other bibliographic tools include the Corpus diacrónico del español (CORDE) and the Corpus de referencia del español actual (CREA).
Diccionarios.com
Includes language dictionaries for Spanish, English-Spanish, French-Spanish, and Catalan-Spanish.
Dictionaries and Grammars of Indigenous Languages of Mexico
Organized by language family, in alphabetical order, this list includes other related books published by the Summer Institute of Linguistics or the Instituto Lingüístico de Verano (Mexico). English/Spanish.
yourDictionary.com
"The Web's most comprehensive and authoritative language portal with every resource needed for language study in more than 300 languages."
Michaelis Moderno Dicionário da Língua Portuguesa
An online Portuguese language dictionary.
Verbix
Verbix is an independent non-profit organization that aims to promote and protect linguistic diversity. This site contains verb conjugations for 300 languages. Spanish, Portuguese, Catalan, Valencian, Asturian, Basque, Miskito, Papiamento, St. Lucien, Portugûes de Corlai, and Jamaican are among the languages of interest to Iberian and Latin American Studies.