As a project while learning Java programming, Morn of Executus-EU decided to create a tanking simulator and run some experiments. The simulator, which can be downloaded here, lets the tanking classes input their "to be missed", block, dodge, parry, block value and armor, and run it against the boss's attack damage range and speed. You can also use it to compare how much damage/crushing blows/burst damage paladins, druids and warriors would have while tanking the same fight. As a cool side bonus, the site also shows a "combat log" of the fight against the boss, complete with your hits, misses and damage.
A better theorycrafter than I could have some fun with this, but Morn found that assuming comparable gear, a druid takes 15 percent more damage than a warrior and 10 percent more than a paladin. He notes that it could be a good way for tanks to figure out what stats they need to improve to become better at damage absorption.
Who do you think makes the best tank? What information can you gain from this simulator?