Dictionaries

Gran diccionari de la Llengua Catalana (Great Dictionary of the Catalan Language).
Catalan-Valencian-Balearic Dictionary, that is, the famous Alcover-Moll dictionary, with all the variants of the language.
This is a free translation dictionary for English/Catalan, Catalan/English. Look at the bottom of the column on the left side, and click on "Diccionaris complets".
Online text translator, from catalan to spanish, or english, or french, and from these, to catalan. Useful for short translations: it accepts a maximum of 2500 caracters (one page of text, aproximately).
If what you want to translate (between many pairs of languages including the catalan) is a complete Web page, then you copy your page's URL adress, go to this page of translation, and paste it in the box for translation.
Another possibility for automatic translation is Opentrad, where you can translate between: Spanish-Galician, Galician-Spanish, Catalan-Spanish, Spanish-Catalan, and Spanish-Euskera (Basc). It works with either text, files, or Web pages.
A very good dictionary of Catalan/Spanish, Spanish/Catalan, is the Valencian/Spanish and Spanish/Valencian, of the Conselleria d'Educació de la Generalitat Valenciana (regional government). It can be used as if Valencian and Catalan would be the same language!
At the top of the same previous page, you can download a software program called "Salt", which is a text translator Valencian/Spanish and Spanish/Valencian (freeware, to be installed on your PC).
Dictionary of translation English/Spanish, Spanish/English. Also monolingual in English. A good one.
Spanish dictionary, by the “Real Academia Española”.
Translating dictionaries, bilingual, in many pairs of languages.
Online dictionaries from Gabinet de Terminologia de la Universitat de les Illes Balears (University of the Balearic Islands): there you will find some general dictionaries, as well as specialized ones in almost every area.
Dictionaries on almost all the subjects and in all languages, from "Universia".
A curiosity: a dictionary in Catalan-Spanish-Latin-French-Italian. Facsimile reproduction of the 1839 edition in Barcelona. First volume. With the sub-title: "For a society of catalan people"
Ditto, Second volume .
And finally, a music dictionary.