The University of Chicago Spanish Dictionary, Spanish-English, English-Spanish by 
The Oxford Spanish Dictionary by 
A New Reference Grammar of Modern Spanish by Allows you to type Spanish accents and other Spanish characters without a Spanish keyboard. You can edit your text in the box and then copy it to your document, email, etc.
These tools can translate entire blocks of text, but beware - they don't always produce proper grammar!
Some of the library databases come with built in tools to focus your search.
These sources provide information on the Spanish language and culture.
