In no particular order, here is my short list for recommended resources of recent publications on Koine Greek.
Christian Oxyrhynchus: Texts, Documents, and Source by Lincoln Blumell, Thomas Wayment
The Letter to the Romans: A Linguistic and Literary Commentary by Porter
Linguistic Analysis of the Greek New Testament: Studies in Tools, Methods, and Practice by Porter
Fundamentals of New Testament Textual Criticism by Porter and Pitts
Structural Lexicology and the Greek New Testament by Todd L. Price
Revisiting Aspect and Aktionsart: A Corpus Approach to Koine Greek Event Typology by Francis G. H. Pang
Modeling Biblical Language: Selected Papers from the McMaster Divinity College Linguistics Circle
The Multilingual Jesus and the Sociolinguistic World of the New Testament by Hughson T. Ong
Hellenistic and Biblical Greek: A Graduated Reader by McLean (the best Koine Reader out there IMO).