For starters here's my toon for whenever I reference my gear, info: Spoonybard @ US-Azuremyst. http://www.worldoflogs.com/guilds/196640/
What I focus on: not just doing more dps solely, but also making sure you're not getting wrecked on every fight.
If you would like to me to help you increase your dps here's what I'll need:
Toon's name & server, so I can see current gear setup.
Logs of at least two weeks of information, so I can see damage flow on you and see how different gemming/reforging would work and also what you're currently priortizing.
Raid comp, so I can see what externals could be used on you and what your other tank is.
Current level of raiding content, this drastically effects what kind of gearing you're going to shoot for.
Also for you to be knowledgable out the class/spec as whole so when I'm referencing things it will expedite the process. Tyvi does an excellent job already if you haven't caught up on his guide to this tier: http://elitistjerks.com/f72/t130560-...e_before_cool/
You can also PM on my server for more info and I'll add ya to realID!!! Not going to post Btag here for obvious reasons. =]
Now I'm definitely not the best at this, but I do pretty well for myself in my raids and on WoL so just throwing this out to the community to see if people are interested. Only really focusing on 10 man tanks since it's really all I'm physically experienced with. You can definitely hit up the dk chat #Archerus: http://sonofalich.com/?p=1257 if you have lingering thoughts/questions about our class as whole.
There's also still a lot of debate with what stat priorities are and etc since sims are still not updated for current content. I'm going off what works for me and I've seen work for others, which is what I'm currently basing my stat weights off of.