Awhile back, I posted a note referring to a book edited by Al. N. Oikonomides called Abbreviations in Greek: Inscriptions, Papyri, Manuscripts and Early Printed Books (amazon.com).

I've had the book for a few weeks now. It contains four monographs (some short, some long, some with extensive catalogues and other such material) having to do with abbreviations in Greek. These monographs are:

"Abbreviations in Greek Inscriptions" by M. Avi-Yonah
"Abbreviations and Symbols in Greek Papyri" by F. G. Kenyon
"Abbreviations in Greek Manuscripts" by T. W. Allen
"Abbreviations in Early Greek Printed Books" by G. F. Ostermann and A. E. Giegengack.

I think it is safe to say that if you have questions about abbreviations or ligatures in Greek text, this book is a great place to start looking. Particularly helpful for my purposes are the tables of abbreviations found in Greek incunabula (Ostermann & Giegengack's article) and T.W. Allen's article as it deals with stuff one finds in Greek MSS.

If you're really into this stuff, you'll probably want to check out the Byzantine Greek Fonts mentioned by Suzanne McCarthy on her blog, Suzanne's Bookshelf.