On (moderated:no free ads) there is loads of information (that I myself have compiled from government documents and translated it into Greek) on topics such as living, working, marrying, citizenship, insurance, education in English etc. Check the Greece A-Z section: (moderated: no free ads)
The reason I researched and posted all of this information is because I moved to Greece 6 years ago from America. The advantage for me was that I already knew the language, because I am of Greek descent, but it was still difficult for me to find all of the things I wanted in public services and so on.
If you have any questions you think I can answer, please ask through this thread or the website. I wish I had discovered this forum when I moved here!