Translation: Spanish Resources

Spanish Dict

WordReference Spanish-English Dictionary

University of Chicago Spanish Dictionary (Print) 

Diccionario de la lengua española (online, also available in print)

Strictly Spanish Translation Resources: an online resource page with a large collection of specialized glossaries 

Technical

Routledge Spanish Technical Dictionary

Legal

Butterworth's Spanish/English Legal Dictionary

Spanish Law Dictionary (Ebook)

Business

Business Spanish Dictionary (Ebook) 

Slang

McGraw-Hill diccionario del argot: el sohez (Ebook)

Pardon my Spanish: Pocket slang dictionary (Ebook)