If you ask us to prove that plural marriage is Biblical and acceptable to God, we are going to ask if you've read the first item in each section here first!:
Tom Shipley's excellent book, Man and Woman in Biblical Law, download it here (free for digital, or buy the bound version). Tom's 2nd volume in this series is now available for download also: They Shall Be of One Flesh
The now-famous 1869 book by "James Campbell" (psuedonym): The History and Philosophy of Marriage or Polygamy and Monogamy Compared. (free)
This book has been going around the Internet a lot (it's public domain); just for the record, the text in this copy originally came from the defunct bfree.org website, you can find it on the Internet wayback machine from April 1998 (though it was available there in Jan 1996 already).
If you are seriously researching the history of Christian polygamy, this book by John Cairncross is a must. Unfortunately it's not available digitally, and it's out of print, so will cost you dearly. Here's a review. Google has posted most of the 1st chapter online here.
Jay Carper's Commentary on Marriage in the Bible is a great resource. Jay has also made it available for free here. (Please consider a donation.)
Sam Chapman's Polygamy, Bigamy and Human Rights Law book. (free)
James Wesly Stiver's Eros Made Sacred or The Biblical Case for Polygamy (free)
The rediscovered classic: "Thelyphthora, or A Treatise on Female Ruin" by Martin Madan, is available on Google Books: Volume 1 and Volume 2. It's not an easy read in this 1780 edition, but the content is very worthwhile. (If you are aware of this book being available in updated fonts, please let us know where.)
Don't expect to agree with everything found in each book - but you should find something helpful in each resource.
Divorce and Re-Marriage: Recovering the Biblical View (online and Word version), or buy at Amazon.
This is an interesting book, the author William F. Luck, is well-known in evangelical circles. He's written what we find a very Biblically-sound, scholarly, complete treatment on divorce and remarriage. In doing so, he found he couldn't ignore the implications regarding plural marriage, and was somewhat surpised by what he found. He's not 'advocating', he's just being honest about the truth he found in the Word, making for a compelling argument -though he took a fair amount of grief in theological circles for being willing to make it. Kudos to Professor Luck for being willing to be honest on the subject, and for making the book available at bible.org. Some of you may wish to start with Appendix B (On the Morality of Biblical Polygny). (We've started a discussion thread on this book here.)
A good Biblical overview of polygamy by a Pastor.
Sam Chapman's venerable British polygamy site.
Here's a nice site with lots of easy reading, good information.
An active Christian polygamy discussion group, where many of our friends participate.
You'll find many other useful links have been posted by members in our Links of Interest forum.
Our Biblical Families Facebook, MySpace, Twitter and Radio links are just to the left. An archive of all our radio broadcasts can found at the radio site.
e-sword, probably the best free Bible program for Windows or PocketPC. Many translations available, plus commentaries/devotionals.