So i have found this exploits in ulduar.......
1)Flame Leviathan
Go take a tank clear the road to the boss and then attack him...move fast behind a pillar, before he gets to you(i suggest using a speed hack), and then start shooting in the pillar, you should get no damage and your health will stay up while the boss will take damage - good way to solo it, works on heroic too but dont shoot with anti aerial rockets cause that will hurt your tank too.
Second methos is to use speed hack and bring Flame to the camp near the entrance, there he will fight with mobs too.So even if you die just wait and he will die and then happy looting.
-tested on WoW Ultimate 3.1.3
2)Other bosses
Just get a mage to blink through the door behind leviathan and you wait there with a tank, the mage should bring the mobs/boss out by blinking through the door and then you should be able to kill it.
-tested on WoW Ultimate 3.1.3
Hope this helps guys...i don't know if it works on other server...please test and post respons.Also on my server the admin spawned Naxx over Ulduar so you can't use fly hack to bring the bosses to tanks...