Ichthys - Bible Studies for Spiritual Growth, By Dr. Robert D. Luginbill
A great teaching ministry by Dr. Robert D. Luginbill (a Classics professor at the University of Louisville) dedicated to helping the spiritual growth of other believers. Contains systematic Bible Basics series, the Coming Tribulation, the Peter Series, the Satanic Rebellion, and more.
Bible Academy, By Curtis M. Omo
A great verse by verse teaching ministry by Curtis M. Omo, covering various books of the Bible.
BibleDocs, By Steven W. Tammen
Another teaching ministry I highly recommend, written by a good friend and peer of mine.
Resources for Teachers and Lay Christians (non-teachers) Both
Books about the Bible Itself
“A Students Guide to Textual Criticism of the Bible” - By Paul D. Wegner
Books on Church, Ancient, and Jewish History, Culture, and Society
“A History of the Ancient World" - By Chester G. Starr
“A History of the Christian Church” - By Williston Walker
“New Testament History" - By Richard L. Niswonger
“The Greeks: History, Culture, and Society” - By Ian Morris/Barry B. Powell
“A History of Israel From the Bronze Age Through the Jewish Wars” - By Walter C. Kaiser Jr. and Paul D. Wegner
Commentaries, Dictionaries, and Surveys
“Unger’s Commentary on the Old Testament” - By Merrill F. Unger
“The Bible Knowledge Commentary” - Old and New Testaments
“The New Unger’s Bible Dictionary” - By Merrill F. Unger
“A Survey of Israel’s History” - By Leon J. Wood
Bible Atlases and Geography
Oxford Bible Atlas” - By Adrian Curtis
“The New Moody Atlas of the Bible” - By Barry J. Beitzel
Vocabulary for Greek and other classical languages