Here's a thought: How feasible would it be to create a mod that allowed you to "possess"/take over the bodies of NPC's. Sort of like an evil spirit that jumps from person to person. A polymorph/shape shifting mod could reset the player's physical characteristics (name/head/body/ect.) to match the NPC's, but taking it a step further, would it be possible to create a mod that changes the player's body/head/stats/name and ITEMS to match the target NPC. I figure the target NPC would have be stored somewhere until you were done using that body, then the old NPC could appear, with any items you had on your person, where the player is standing the next time you take another victim. Bottomline: When you take a body, your stats and items are reset to match your target's, and your position in the game is set to match the target's giving the illusion of taking over that body. In reality you've just replaced the NPC with a clone, but the original NPC has disappeared somewhere else. When you swap bodies again, the original target appears where you are standing and you immediately move to where your new target was positioned. Giving the illusion that you controlled the body up until that point. There would have to be a script controlling items. If I'm running around as Vivec and I pick up a cool weapon, but then I decide to take over the body of someone else, say a little bar wench named Marcilla and I forget to leave the cool weapon someplace where I could retrieve it later, suddenly Vivec has the cool weapon in his possession. I also figure it would be realistic if your old host body tried to kill you after you left their body. Just a thought.
there is a topic about a WIP polymorph spell here http://www.elderscrolls.com/forums/index.php?showtopic=518795
hm.. for morrowind it would be kinda hard. for oblivion you might be able to mod the Skull of Corupption scripting to do that (for those ignorant the skull of corruption is a staff that makes clones of the victum :p)
I'm glad to see the idea is out there for Oblivion, but my computer sucks too much to run it. I'm still running around in Morrowind mode and was hoping someone had taken up the challenge. =)