Here is an interesting twist on the online dictionary. Lingro offers the traditional, Wordreference-style dictionary, but also has the facility to translate individual words on any website page you choose. You just enter the URL of the web page, then the Lingro allows you to see instant translations as you click on words. These pop up in a little window near to the chosen word.
This is a very good tool for the non-specialist linguist, though skilled linguists might also make some use of it from time to time.
By the way, the Lingro bilingual dictionary is very fast and quite detailed. It claims to be the fastest on the web.
However, I have not yet come across anything that will take me away from Wordreference, with its detailed (if not infallible) translations and useful forum.