A few posts back I mentioned a great series that a blog called Reading Acts is doing, suggesting five good commentaries to own for each book of the New Testament.
There is also a site that I frequent, called Best Commentaries, that compiles and averages user reviews and ratings to rank the best commentaries on all the books of the Bible. The rankings are somewhat subjective and open to disagreement, but the site is quite helpful all the same. You can look up commentaries by book of the Bible or by commentary series. The site also notes the “academic level” of each commentary, so you know if Greek/Hebrew is required to understand it (“Technical”), if it’s ideal for sermon prep and heavy exegesis (“Pastoral”), or if it’s of a more “Devotional” nature.
(Of course, I think some commentaries fit into all three categories at once.)
Best Commentaries has served me multiple times already as a helpful guide. I highly recommend it.
Words on the Word 