IMPORTANT NOTE:
Due to the limited availability of e-commentaries from publishers, most series listed below are incomplete. Click a series title to see the biblical books available in that series.
Note: The volumes in the Ancient Christian Commentary on Scripture series focus on interpretations from the Early Church era (e.g. Augustine, Clement of Alexandria, John Chrysostom, etc.) rather than more modern scholarship
Note: The volumes in the Reformation Commentary on Scripture series focus on interpretations from the Reformation era (e.g., Luther, Calvin, etc.) rather than more modern scholarship
A site that can be very helpful for looking up passages, finding Strong's numbers, and seeing a passage alongside the original Greek or Hebrew (look for the "Tools" button after a search). Be wary of the commentaries and reference resources on this site, as they are generally older, public domain sources.
A useful site for finding verses, viewing a passage in English alongside Hebrew or Greek in an interlinear Bible, and looking up Strong's numbers or TDNT/TWOT references.