Found a new Glitch/exploit today. After completeing dawnguard, and acquiring Summon Durnehviir Thu'um ; and his shout Soul Tear... If you use Soul Tear on a dragon (of any kind) the dragon will sometimes glitch. He will die but not die (assuming that since the Thu'um locks the soul inside the body and forces that creature to work for you) he will also not attack you. Be aware that if the dragon is at zero life and still flying he will not land but just fly around you. But if the dragon is on the ground when he reaches zero life... he will just sit there and still be a valid target for destruction spells, one handed weapons, two handed weapons, archery. My skill in one hand is steadily climbing, and so is my destruction skill. Also as a note, since he has zero life he can not be healed so restoration will not gain experience. Also since he will not attack armor, and block will also not gain any experience....!
I have tested this a couple of times, And will continue to test this. I am sure this is a glitch and was not intended to do this... Still a lot of fun! And so far no major problems with the game as the exploit with casting magic at Vilkas during the test of arms quest.
I would love to hear of any other exploits that do not cause major problems with the game.
ADDENDOM: After leaving the first time when he was flying and still barely alive, when I returned he was sitting on the ground and I Shot him and dropped him to zero life and he would not die so I started hacking and casting, and posted this post!
ADDENDOM: I left and got a two handed weapon and some magica regen stuff, and upon my return the dragon was actually dead, and I got the dragon soul and multiple arrows That I shot into him.