The field of biblical studies is full of excellent resources - so full that many of us have no idea many of these resources exist. Unless you have an encyclopaedic memory you will need a guide to inform you and remind you of the most important works available to you as you research. John Glynn's Commentary and Reference Survey is designed for that very purpose.
There are other good commentary surveys available (Carson's NT Commentary Survey and Longman's OT Commentary Survey), but what makes this one different is it is not limited to commentaries. Not only will you find lists of OT and NT Introductions, Surveys, and Theologies, but also a host of works on subjects like: the Septuagint, History of Interpretation, Rabbinics, Dead Sea Scrolls, Greco-Roman Religion, and Church History (including sections on the Reformation, Jonathan Edwards, and the Southern Baptist Convention) - just to name a few!
Of course its greatest strength is also its greatest weakness. Because of the vast number of sources included there is virtually no room for commentary on the comparative value of one work over another. Those works the author considers the "best" in a particular field are in bold type, but aside from that the author aims mainly to make the reader aware of what is available. The book is already about 380 pages - one can only imagine how long it would be if the author commented on every book!
This book is in its tenth edition and was last updated in 2007 - which means if you are looking for the latest commentaries you will need to look to a more recently updated guide such as Carson's mentioned above (revised in 2013). But for breadth and scope of coverage Glynn is still an excellent resource.