Glosarios y diccionarios de especialidad

Nearly 750,000 Google results for "online glossary"
Well, you would try Google, wouldn't you?

Business Glossary (Andy Miles)
English-Spanish, Spanish-English business glossary, with over 8,000 items.

Computer terms (TechWeb)
Provides definitions of over 20,000 computer terms.

Desktop Publishing (About.com)
Graphic design, paper, printing, software, and typography terms. The usual good results from About.com.

Directory of glossaries (Glossarist.com)
Describes itself as a "searchable and categorised directory of glossaries and topical dictionaries". Excellent - and one to bookmark!

Economics (About.com)
Another useful glossary from About.com.

Film glossary (Internet Movie Database)
Excellent - as you would expect from the incomparable IMDb!

IT terms (Whatis.com)
Defines thousands of information technology terms.

Law (Law.com)
To translators, the dictionary is probably the most useful of Law.com's extensive resources.

Legal dictionary (Nolo.com)
Nolo.com has both a legal dictionary and also an encyclopaedia on legal topics.

More glossaries (elcastellano.com)
Vast A-Z of glossaries on subjects ranging from accounting to wine...

Quotations (Bartleby.com)
Searchable database of quotations in English (also dictionary and encylopaedia).

Slang (Peevish.com)
Dictionary of UK slang. Try their links section for other forms of slang (Australian, US, specialist...).

Statistics
An excellent English-Spanish/Spanish-English glossary of statistics from Spain's Instituto Nacional de Estadística.

Webopedia.com
Online dictionary and search engine for computer and Internet technology. Results generally excellent, as are the links provided.