Do you know that Wiley-Blackwell has a “Companions to Religion” Series of books? I just discovered this and two volumes seem very useful to me: The Blackwell Companion to the New Testament (ed. D.E. Aune, 2010) and The Blackwell Companion to Paul (ed. S. Westerholm, 2011).
Needless to say, editors Aune and Westerholm worked hard and successfully to put together truly impressive contributions. In fact, for the book on Paul expect a substantial review later this year.
For now, you may be interested in knowing that
(1) The NT volume is offering a free chapter on “The World of Roman Hellenism” (Aune)
(2) The Paul volume has a free chapter on “Pauline Chronology” (Reisner)
Sadly, while these are free, the rest of the chapters total nearly $400 (each volume is $199!).