There are quite a few online German English dictionaries. None of them has all of the answers. I quite like webtranslate, for European Community stuff IATE is OK and both dict.cc and Leo have a lot of entries. Just search for „englisch deutsch Wörterbuch“ and you will find a long list of online dictionaries, or dictionary applications, some free, some not. In daily work, I use Kim's little helper II which uses all four of the above at the same time.

See the weaknesses of online dictionaries.