I re-certified this year. Prior to the devastation in the stock market I thought this would be my last exam, but now it looks like I'll have to take it 2 more times. You younger guys should plan to take it 4 or 5 times and you'll probably be taking it in Hindi or Mandarin Chinese near where you work.
Here is my review of study materials.
One of the best resources is the book I used 10 years ago, Kahn & DeSio. It is the best bang for the buck - inexpensive and densely packed with good info.
I bought a copy of the 2006 Dannemiller review course on eBay ($150) and watched that. This was probably the best review material but at 40 hours it was very time-consuming. If you watch it on your computer with appropriate software you can do a screen cap of each slide for quick review later (I used GOM Player and set it to do a screen cap whenever I hit ENTER).
I also read Benzon but found that it didn't go into much depth and I doubt it would serve as a single resource. There were some significant errors and omissions. For example, in the discussion of Prialt's side effects there was no mention of CNS changes and in the chapter on pain management in the critically ill there was no discussion of which drugs require adjustment in renal failure.
I also looked at the "Big Yeller Pain Killer" from boardprep.com. Words cannot describe how little I think of this material. As MAD Magazine used to say, it's useful for wrapping fish or training puppies. In addition to being woefully incomplete in its coverage of the ABA outline we are treated to some surprising "facts":
"Spondylosis refers to a defect in the lamina that may separate the anterior body from the posterior elements".
"Neuropathic pain states involving the central nervous system are often referred to as 'sympathetically mediated.'"
"Causalgia . . . is a subset of CRPS I and is known as CRPS II".
Cervical epidural steroid injections are suggested for tension headaches.
The section on RA doesn't mention anti-TNF agents or DMARDS.
There is this silly military theme throughout, with quotes by Sun Tzu, etc, and calling the examinees "rangers" as if we were waging war on the examination.
A colossal waste of money and could conceivably lower your score.
No matter how much you read you can't escape the fact that a significant part of the exam covers things you can't prepare for. You are given case scenarios where the correct answer is missing, e.g., "I would never be so stupid as to get myself into this predicament", or "In real life I'd fire this patient but for the exam I will suggest drug rehab" or "I would refuse to do this consult because working with this doctor could lower my IQ and destroy my reputation".