Grand dictionnaire terminologique (Office québécois de la langue française)
Termium (now free!)
FranceTerme
Lexique des mots des affaires (AFPA)
IATE
Termium (subscription required)
Larousse
Wordreference

Muleta, European encyclopedia of urban planning and housing
If someone knows of a good on-line FR<>EN architecture and design glossary, please post a comment!

Lexique bancaire UBS (FR, EN, DE, IT)
GDF-Suez financial glossary (English)
Institute of International Auditors
International Trade Centre glossary on trade financing terms (FR, EN, ES)
IMF multilingual directory

Skyguide Air Navigation glossary
French Civil Aviation Authority glossary
Dassault Aviation glossary

European Environment Agency’s Environmental Technology Discovery Service (multilingual glossaries)
FAO’s AGROVOC (multilingual)

Petroleum and Natural Gas International Standardization glossary

Alaide (FR)