As an American living and working in Germany, I must say I could not do without LEO. My German is very good, but I still lack just the word I need sometimes, or hear a new word in a meeting and note it for reference. LEO usually comes through.
Here are some from my bookmarks:
Uses the LEO Engine and has links to several other on-line multi-lingual dictionaries.http://www.yourdictionary.com/languages/germa...
Machine translations in many languages. Usually really rough, but a starting point when translating something. It also lets you translate web pages (machine again) on the fly.http://www.t-mail.com/t-text.shtml
Of course, on the machine front, you have to mention Babel fish:http://de.altavista.com/
I would certainly defer to the professional translators out there for intensive translation needs, but when I started learning German I used these machine translations to get me going.
Since many of the links in this thread were for references, I'll throw this in as well:http://www.infoplease.com/
For unit conversions, that we engineers seem to need, I use the following, although I just saw the one that was given above and it looks very useful as well:http://www.convertit.com/Go/Entisoft/Measurem...
vi, Thanks for coming up with this idea!