On ScribD there is a downloadable PDF by Charles A. Sullivan full of very useful information about working with Patristic Greek, websites, tips, etc. It’s here.
Thanks to Robert Bedrosian for pointing out that a search for “patristics” and “syriac” will produce results of considerable interest. The same is true for “coptic”.
You have to register for a free account, and not all material is downloadable; but much is. I suspect at least some of this is less than legitimate; other material; such as the PDF above, is undoubtedly legal. I was amused to discover some material from my own websites appeared, reformatted, as well (which is all to the good, of course).