Web Services
Multilingual
Word Reference: English to/from French, Spanish, Italian
Lexilogos: dictionaries in many languages
Reverso: dictionaries in many languages
Language Tools: google language tools (Systran)
English
Free Dictionary: includes thesaurus and financial dictionary
French
French English business glossary: a small business glossary
Software
kdict: a dict client for KDE
Commercial
Proz is a translator marketplace