Hi Konstantin, folks.
I've been using this online Google dictionary (which is actually based on the latest Collins dictionary + extra stuff from the web):
Name: Google En-En (Collins)
URL: http://www.google.com/dictionary?aq=f&langpair=en|en&q=%GDWORD%&hl=en
Maybe it makes sense to add it by default to GoldenDict. The dictionary is great (provides clear explanations, phrases, examples, etc), the layout in GoldenDict is very good, the site is fast.