Philippians and Colossians
The good news is that both Philippians and Colossians have been blessed with excellent works in recent years. The bad news is that the average pastor on a limited budget will have to make some hard choices when browsing turns to buying. Let's start with Philippians.
It's been over twenty years since I preached through Philippians. Among the works available at that time, none compared with Gerald F. Hawthorne in the Word Biblical Commentary series (Word Books, 1983, 232 pp.). Although I deeply disagree with his interpretation of Philippians 2:12-13 (he believes the exhortation is corporate and not intended for the individual believer), this is an excellent treatment of the letter that every pastor should own.
Hawthorne has in a number of ways been surpassed by the appearance of commentaries by Peter O'Brien and Gordon Fee. O'Brien has written for the New International Greek Testament Commentary (Eerdmans, 1991, 597 pp.) and has provided us with what is arguably the very best commentary on this letter (very similar in style and substance to his work on Ephesians in the Pillar series). Fee's contribution in the New International Commentary on the New Testament series is superb as well (Eerdmans, 1995, 497 pp.). If the combined effect of these three fails to satisfy your exegetical hunger, you can find more help in Moises Silva, Philippians, Baker Exegetical Commentary on the New Testament (Baker, 2005, 248 pp.). Be sure you get the Second Edition of Silva's work.
There are three, shorter, works on the English text. I found especially helpful The Message of Philippians by Alec Motyer in The Bible Speaks Today series (IVP, 1984, 234 pp.). Also useful is the NIV Application commentary by Frank Thielman (Zondervan, 1995, 256 pp.). Finally, although very brief (124 pp.), Basics for Believers: An Exposition of Philippians (Baker, 1996), by D. A. Carson is quite good for illustrative help and contemporary application.
If you obtain O'Brien, Hawthorne, and Fee, you will be well set for study of this Pauline epistle.
I'm a bit more familiar with recent literature on Colossians, having published only a year ago The Hope of Glory: 100 Daily Meditations on Colossians (Crossway, 2007, 362 pp.). Although not technically a commentary, I think you'll find it helpful for theological and practical insights into Paul's argument.
It seems as if I keep coming back to Peter O'Brien when talking about the Pauline literature. He has again written one of the better commentaries on Colossians in the Word Biblical Commentary series (Word Books, 1982, 328 pp.). Unfortunately, the new commentary by Douglas J. Moo came out too late for me to use in my book, but from everything I've read in it this definitely has become the new gold standard in Colossians studies (Eerdmans, 2008, 471 pp.). Moo has written on Colossians and Philemon for the Pillar series.
This next recommendation is solely for those pastors who are serious about grappling with the Greek text of Colossians. Murray J. Harris wrote the inaugural (and as far as I can tell, the only) volume in the Exegetical Guide to the Greek New Testament (Eerdmans, 1991, 310 pp.; can anyone tell me if subsequent volumes in this series have been released?). This is not a commentary per se, but focuses on virtually every grammatical issue and important interpretive option in Colossians and Philemon. I can't recommend it too highly, especially for the pastor who has lost his facility in the original text and is committed to regaining it.
James D. G. Dunn has done a good job on Colossians and Philemon for the New International Greek Testament Commentary (Eerdmans, 1996, 388 pp.), but if you have O'Brien, Moo, and Harris, I don't think you'll find it necessary. The NIV Application volume (Zondervan, 1998, 389 pp.) by David Garland is very helpful on the English text.
I'm probably somewhat alone in this final evaluation, but I did not enjoy or profit from Colossians Remixed: Subverting the Empire (IVP, 2004, 256 pp.), by Brian J. Walsh and Sylvia C. Keesmaat. In fact, I was consistently annoyed by it. I couldn't help but get the impression that they had a previously formulated political agenda and turned to Colossians to find (unsuccessfully, in my opinion) biblical support for it. If you are persuaded, as they are, that western capitalism and American foreign policy are largely responsible for the ills of our society and those of the world at large, you will probably enjoy this book. But don't buy it. I'll be happy to sell you mine (pressure me, and I might even give it away!).