Here's a quick list from the sticky on WoW US forums:
Will update more as I get some other parts of this website finished.0.8.1 Protection Mods
Tankpoints is as good as it gets in terms of itemizing gear. I do not suggest using the values listed to compare to other users, but it certainly will help you in determining damage reduction and what is the most effective combination of gear against the creatures you are fighting. Get it here:
A newer Threat Meter which is considerably more flexible and functional than KTM Threatmeter. You will need to be sure to get continuous updates to this. Learn more (and download) here:
Combat Monitor, SWStats, and WWS
Cream of the crop. Picking up each of these three mods and working them in conjunction with the raid will give you the best idea of your overall performance. Combat Monitor (not sure if this has been updated yet) is Satrina's mod, very useful for checking how you did after combat; SWStats is a complex DPS meter for your raid; Warcraft Web Stats (WWS) is a combat log parser that lays out detailed reports of your raid into HTML files.