The Three Ways
In all the many and various theological works I have read, attempts to reconcile the ideas of "justification by faith" and "judgment by works" have always boiled down to three basic options:
1) Get rid of one.
2) Hold that both are true, but are different events and criteria. (ie "faith" and "works" are different criteria, and one is judged at conversion and the other after death.)
3) Hold that both are true and the same thing. (ie the phrases "justification by faith" and "[positive] judgment by works" are synonymous because "faith" and "works" are synonyms as are "justification" and "positive judgment by God".)
Conservative Protestantism has historically opted for 1, saying that any judgment by works is about rewards but not eternal destinies, or saying that passages about a final eternal judgment by deeds are hypothetical and no one can actually live up to God's standard.
Many recent scholars have opted for option 2, arguing that justification by faith is an event that happens at conversion and that a judgment by works happens at the final eternal judgment. Thus people come to faith and are justified in the present, and will be judged by their works in the afterlife. The difficulty comes in making sense of this proposed double-justification scheme. The simplest way to do it is to say that to those who come to faith, God gives them the spirit and union with Christ which sanctifies them and empowers them to live a life pleasing to God which results in them passing the final judgment according to deeds. Virtually all modern Protestant scholars I have seen write on this subject, would opt for some variation of this view (eg NT Wright, EP Sanders, Garlington, VanLandingham, Yinger, Stanley, Bird, Rainbow) and it seems to have been Augustine's view and is also pretty much the modern Roman Catholic view.
The third option has been written off without due consideration, and I believe it is the correct one. I think the cause of its undue dismissal is that protestant tradition has attempted to define faith fundamentally over and against works, as meaning "belief and not doing". Yet all the recent linguistic studies of pistis have concluded that it means faithfulness, steadfast loyalty, and perseverance. Is it possible to be "faithful" to God without "doing" God's will? Hardly. But as soon as we say that faithfulness to God absolutely necessitates the doing of God's will, and employ the NPP observation that the "works of Law" being contrasted to "faithfulness" by Paul are "Judean customs" rather than "the doing of God's will", then the dichotomy between faithfulness and works melts away and Paul's theology turns into: "we are judged by God on our faithful obedience to God's will rather than the following the customs of Judea". Justification by faith and judgment by works collapse into a unity, all the difficult questions are answered, and the resultant theology is simple, coherent, and somewhat self-evident. While option 2 is based on Augustine's theology, I think option 3 coheres much better with the pre-Nicene Fathers.