What encounters can be made easier by using pet for some tanking?
So far I know:
Deadmines - Foe Reaper 5000
Lost City - High Prophet Barim - tanking the phoenix
Halls of Origination - picking up the snakes - not exactly pet tanking, but still.
Stonecore - Ozruk
SFK - Baron Ashbury
Throne of the Tides - Faceless Watchers
What are your ideas? Maybe some bosses can be tanked by pet just to ease healer's job via mend pet?
Keep in mind, that pet's tanking benefit is in 90% AoE reduction and in extra healing. Pets can stand if fire and void zones. Blood of rhino, glyphed mend pet and silverback give you ~6.5k HPS on pet without healer. However, pets have significantly lower HP pool than tank (about same as hunter), are not good for fights with picking many adds, and are terrible for kiting fights.