In a previous post here Peter Head draws the attention to a variant reading in Heb 1:8 involving a citation from the Septuagint. I would like to remind the readers that Martin Karrer, Wuppertal, Germany, is heading a project to create a new tool for the study of LXX citations in the New Testament. I attended a presentation of the project last year at the SNTS 63d meeting in Lund. There is a description of the project here.
Regarding Hebrews and the LXX, Karrer has published an essay, "The Epistle to the Hebrews and the Septuagint," in Septuagint Research. Issues and Challenges in the Study of the Greek Jewish Scriptures (eds. W. Kraus and G. Wooden; SBL.SCS 53; Atlanta / Leiden, 2006), 335-353.
There will be a session devoted to the subject of LXX and NTTC at the SBL in New Orleans on Monday 23 November, 9:00–11:30:
New Testament Textual Criticism (The Two Bibles: The LXX and NTTC),
Leonard J. Greenspoon: “If I forget thee…: Remembering, and Forgetting, in ‘Scriptural Citations’ (20 min)
Martin Karrer and Ulrich Schmid: LXX Citations in their NT Versions
Kristin De Troyer: Quotations of "the Septuagint" in the NT
William Adler, Respondent