Can I get any advice for a Dk blood tank?
I’m only 65 and have been running a few outland dungeons. So far, mostly pretty good. I do have trouble holding aggro sometimes even with Death n’ Decay.
A few caveats:
Yes, I use Heart Strike when practical. Sometimes with mobs of mobs it seemed fairly useless for aggro, though.
Yes, I use Death n’ Decay. I don’t have it glyphed right now.
Yes, I tank in Frost Presence.
I usually follow up DnD with Disease/Disease/Pestilence to put it everywhere and if my runes are up Blood Boil. If I can pull of all of that reasonably quickly, I can prolly hold aggro, but that doesn’t always happen before people have pulled them off of me. Maybe they shouldn’t be wildly and without thinking unleash their most powerful AoE’s on everything, but let’s be reasonable and assume the DPS is going to ignore everything but their damage meters. 
Please excuse the poor gearing, I’m in outland and grabbign a mix of tankign and dps gear because I’m soloing as well. Also, most items are going out as soon as they come in.
Talents: World of Warcraft
Some of this is experiments I’m doing for fun, so also please excuse the confusion in talents.
I’m planning to remove Dancing Rune Weapon ( I really have never felt like I needed it or that it was remotely interesting or useful). I am planning on removing Bloodworms. They’re funny, but the amount they heal isn’t really that great when I have Death Strike and Rune Tap.
After some trepidation, I really like Death Strike. With the glyph, it becomes pretty pwoerful and often does as much or more than my Heart Strike. The healing is handy return even in dungeons, and with the talents it gives me Death Runes! I can understand whyn some people avoid it, but I enjoy the talent, so I’ll stick with it for now. Plus, part of my character is leaning how I’ll need to tank in Cataclysm, where self-healing will put up a damage shield on DK tanks.
I may grab butchery for the extra Runic Power and I definitely want Spell Deflection. I figure that, plus Vampiric Blood, will make me a good Tank. There are additional utility talents tossed into Unholy and Frost.
So, I’m building towards this: