Mainly EN
Glossarist (many technical glossaries, mainly EN, some other languages)
Lexikon.ch

Mainly IT
http://www.ata-divisions.org/ILD/glossaries.html
http://marcello.napolitano.com/glossaries.html
by Marcello Napolitano (ILD-ATA) http://www.edigeo.it/EdihomI/Sitoteca/dizspset.htm

Mainly FR
www.biblio.usherb.ca/internet/dictext.htm (FR / EN)
www.biblio.usherb.ca/internet/dicspfra.htm (Mainly FR / EN)
globegate.utm.edu/french/globegate_mirror/dico.html
fmc.utm.edu/~rpeckham/DICO.HTM
Dicorama
www.culture.fr/culture/dglf/traduction/Dicmonolingues.htm

Mainly DE
home8.inet.tele.dk/p-spitz/ (mainly DE / EN)
www.jump.net/~fdietz/glossary.htm (mainly DE / EN)

Foreignword (many fields, many languages)

www.mabercom.com/glossindex/index.html (financial dictionaries
www.insurancetranslation.com/Glossary_Agent/ (Mono- & multilingual financial, insurance, reinsurance, risk management, law etc.)

issco-www.unige.ch/resources/Linguistics/
www.admin.ch/ch/f/bk/sp/aides.html (& other translators' resources)
www2.sbbs.se/hp/cfalk/lang.htm#länkar (Cecilia Falk)

www.yourdictionary.com
www.cetrodftt.com
www.admin.ch/ch/f/bk/sp/dicos/dicos.html
www.1000dictionaries.com
pages.inrete.it/farrell/diction.html
www.dictionary.com/Dir/Reference/Dictionaries/
wwli.com/translation/netglos/guides.html
www.olf.gouv.qc.ca/ OR http://www.sma.qc.ca:8080/olf/ (Inventaire des terminologies dans Internet, Gouvernement de Québec)
www-math.uni-paderborn.de/dictionaries/Dictionaries.html
www.cetrodftt.com (The Language Hub), or here
www.emich.edu/~linguist/dictionaries.html (The Linguist List)

Julio Juncal's list of dictionaries & other resources:
members.nbci.com/beate/Glossaries/glossaries.html
www.inet.uni2.dk/~herlahp/translnk.htm
www.geocities.com/Athens/Thebes/9524/

Mainly PT

http://www.jrdias.com/JRD-Links.html