I figure if I am going to provide all manner of information, I'd start at the basics, the talents, and build up from there.
The Elitist Jerks forum for DK tanking goes into detail for raiding, but leaves the heroic DK tank in the dust:
Discussion here should be on DK endgame raid tanking, both 10 and 25-man, biased to progression tanking (as opposed to taking a more casual attitude to your tanking role).As I'm sure the raiding DK tank can read through that and follow that, I want to focus more on us bloody tanks who stick with Heroics.
I will split this out into three parts for the Blood tree, and then another for Frost/Unholy, and once I'm done I will combine them into a one-page guide for easy reference.