Allen, David M. Deuteronomy and Exhortation in Hebrews: A Study in Narrative Re-presentation (Mohr Siebeck).
Asumang, Annang. Unlocking the Book of Hebrews: A Spatial Analysis of the Epistle to the Hebrews (Wipf & Stock).
Bauckham, Richard J., ed. Cloud of Witnesses: The Theology of Hebrews in Its Ancient Contexts (T & T Clark).
Ciccarelli, Michele. La sofferenza di Cristo nell'Epistola agli Ebrei: Analisi di una duplice dimensione della sofferenza: soffrire-consoffrire con gli uomini e soffrire-offrire a Dio. Associazione Biblica Italiana, Supplementi alla Rivista Biblica 49 (Bologna: Dehoniane).
Joslin, Barry C. Hebrews, Christ, and the Law: The Theology of the Mosaic Law in Hebrews 7:1-10:18 (Paternoster).
Marohl, Matthew J. Faithfulness and the Purpose of Hebrews: A Social Identity Approach (Pickwick).
Mason, Eric F. "You Are a Priest Forever": Second Temple Jewish Messianism and the Priestly Christology of the Epistle to the Hebrews (Brill).
McCruden, Kevin B. Solidarity Perfected: Beneficent Christology in the Epistle to the Hebrews (Walter de Gruyter).
Morrison, Michael D. Who Needs a New Covenant?: Rhetorical Function of the Covenant Motif in the Argument of Hebrews (Pickwick).
Rothschild, Clare K. Hebrews as Pseudepigraphon (Mohr Siebeck).
Seid, Timothy W. The Second Chance for God's People: Messages from Hebrews (Wipf & Stock).
Thomas, C. Adrian. A Case for Mixed-Audience with Reference to the Warning Passages in the Book of Hebrews (Peter Lang).
Thompson, James W. Hebrews. Paideia Commentaries on the New Testament (Baker).
Whitlark, Jason A. Enabling Fidelity to God: Perseverance in Hebrews in Light of Reciprocity Systems in the Ancient Mediterranean World (Paternoster).
Backhaus, Knut. Der Hebraerbrief. Regensburger Neues Testament (Friedrich Pustet).
Backhaus, Knut. Der sprechende Gott: Gesammelte Studien zum Hebraerbrief (Mohr Siebeck).
Bauckham, Richard J., ed. The Epistle to the Hebrews and Christian Theology (Eerdmans).
-This book, along with the Bauckham volume above, is a spin-off from the Hebrews and Theology Conference at St. Andrews in the summer of 2006.
Belleville, Linda, Jon Laansma, and J. Ramsay Michaels. 1 & 2 Timothy, Titus, Hebrews. Cornerstone Biblical Commentary (Tyndale).
Docherty, Susan E. The Use of the Old Testament in Hebrews: A Case Study in Early Jewish Bible Interpretation (Mohr Siebeck).
Fudge, Edward. Hebrews: Ancient Encouragement for Believers Today (Leafwood).
Lee, Brian. Johannes Cocceius and the Exegetical Roots of Federal Theology: Reformation Developments in the Interpretation of Hebrews 7-10 (Vandenhoeck & Ruprecht).
Svendsen, Stefan Nordgaard. Allegory Transformed: The Appropriation of Philonic Hermeneutics in the Letter to the Hebrews (Mohr Siebeck).
Allen, David L. Hebrews. New American Commentary (Broadman & Holman). Expected August 1.
Allen, David L. Lukan Authorship of Hebrews (Broadman & Holman). Expected June 1.
Attridge, Harold W. Essays on John and Hebrews (Mohr Siebeck).
Maxey, Lee Zachary. Rhetoric of Response: A Classical Rhetorical Reading of 10:32-12:31 (T & T Clark). Expected March 1.
O'Brien, Peter. The Letter to the Hebrews. Pillar New Testament Commentary. Expected March 15.
Further out, I know that Philip and Loveday Alexander have been contracted to apply their respective specialties in the Judaic and Greco-Roman backgrounds to a new ICC commentary on Hebrews. But they have not started working on the commentary yet, so this will be a few years.
Gareth Cockerill is writing the Hebrews commentary for the NICNT series.
Wolfgang Kraus is also writing a commentary for Vandenhoeck & Ruprecht.
These are the ones I know about. If you know of any more (any language), let me know.