Mezmero (Level 10)

I think one thing people never bring up when discussing these high-end devil fruit powers is the collaboration of individual Haki.  While I exclusively watch the anime it seems apparent that certain fruit users implement Haki with their powers in several ways.  The primary example would be Boa Hancock, a known Haki user and the woman who ate the Mero-Mero Fruit.  While the fruit's initial power seems to be to utilize intense pheromones to cause petrification amongst those with impure thoughts she has obviously taken the ability a step further.  After witnessing attacks like the "Pistol Kiss" and "Slave Arrow" my standing theory is that she uses Haki to manifest said pheromones into corporeal weaponry.  She has also been seen throwing kicks imbued with Haki to petrify normal humans and even Kairouseki upon physical contact.  Of course an alternate theory to this is that as she is kicking her skirt is lifting up revealing enough to turn most men into stone.
 
Now in the current TV arc we see more prominent fruit and Haki users come into play.  Whitebeard and his top commanders are depicted as such.  With the reputation they have as the strongest pirate crew it seems unavoidable for them to combine their abilities with Haki in order to fight the Logia intensive Admirals.  I'd be willing to bet that the initial power of Newgate's Gura-Gura fruit was to merely shake the ground so I figure he uses Haki to send the vibrations through the air itself.  We must not forget that their are implications that the Admirals themselves are capable of using it as well after we see them block one of Whitebeard's air quakes from hitting the execution scaffold.  Seems even more likely when we see Akainu clash with Whitebeard reaching somewhat of a stalemate with their powers.  We also learn that there are ways around Haki's effect on Logia's when we see Aoikiji form a preemptive hole in his torso to avoid Whitebeard's spear.