Resources

ISO639 --- use this to determine your language's ISO code.
FOLDOC -- The Free On-line Dictionary of Computing -- meanings of technical terms.
If FOLDOC doesn't have it, try Wikepedia, The Webopedia Computing Dictionary, or Google (try searching for “TERM definition” or “TERM meaning”)
High-Tech Buzzwords will tell you the meaning of just about any computing or technical acronym! Look up those annoying and cryptic names like GPSD, AARNET and MTA.
The alphabetic file extension list tells you what those file-extension abbreviations like .csv and .php really mean!
dict.org --- various online dictionaries that you can use to help define English words and thus help you create or find equivalents in your language.
Wiktionary is a wiki-based dictionary system available in many languages, to which anyone can contribute. You can use its current resources, and build your own glossaries there.
Language names - how do you write the name of your language?
Plural forms — what plural forms does your language use?
Display settings - what settings are necessary for ideal display of your language?
Quotation Marks - what does your language use for quotation marks? Also how to set language-specific quotes in CSS. Thanks to Jutta Wrage for creating and maintaining this page.
babelzilla -- List of English - <language> - glossaries of terms used in the mozilla extensions
Open-Tran -- site that offers access to the translations of open source projects, as a kind of central translation memory

The most common Net acronyms in Vietnamese lists many online, technical or chat abbreviations in both English and Vietnamese.
Lac Việt English-Vietnamese dictionaries, including their computing dictionary, which is probably the most current computing dictionary available online, although the whole dictionary site is often unavailable
KSVN English-Vietnamese, Vietnamese-English dictionaries which seem to have some words and phrases you don't find elsewhere: their databases are definitely more current than some
The Free Vietnamese Dictionary Project has a really impressive array of Vietnamese dictionaries to and from various languages, and is constantly improving it. This is probably the most thorough and reliable database of Vietnamese dictionaries. They are also available to run offline, on desktop/laptop computers or PDA.
The English-Vietnamese Glossary Service is an excellent initiative, though currently hampered by lack of volunteer time. It should develop into an authoritative resource.

English-Dutch dictionary of the Dutch Translation Project team contains English to Dutch translations of common terms in open-source software that the translators' community has agreed upon. Their section for translators also contains links to other useful resources.