I’m looking for the writings of the Church Fathers online in the original Greek. Unfortunately, the Perseus online library doesn’t cover the Church Fathers, and Google searches get me nowhere because some people are a bit too enthusiastic about their software, which only gives the English translation (possible Google slamming?). So, if anyone can point me to the Greek texts online, I’d be very thankful.
The Wesley Center On-line has links to most of the Patristics in English translation. You may find a link, there, that will take you to the original texts.
A Google of “patrisitcs koine” seemed to turn up mostly classes on the topic, but you might try that search on your own to see whether you can see something I missed.
(It is possible that they are out there in Greek, most easily reached from a Greek language site. If you select Language Tools from the tiny link to the right of the search argument window at the Google main search page, they give you several options to use to search non-English-based web sites.)
The OCA might be able to help, but they would be more likely to have Slavonic and Russian material, since the OCA comes from Russian missionaries. The Greek Orthodox Archdiocese (http://www.goarch.org/) would be a more likely source to point to whatever sites in Greece might have Greek materials. I know that the Orthodox Church of Greece has been developing quite a web presence.