To the best of my knowledge, being attacked on site is specifically due to faction relationship between the player and npcs/creatures. I don't think any mod exists that can alter this relationship on a world-scale. However, such a mod would be pretty freaking awesome.
I *believe* there are other ways to alter an NPC's disposition towards the player so as to make them attack you. In theory I think it would be possible to add a script that is constantly checking NPC's in your cell and if it finds any makes them aggressive (although I don't know for sure how easy/possible it would be to build in exceptions for, say, the Shivering Isles and Mythic Dawn). Anyway, I don't actually know much about Oblivions AI, but based on my experience programming in general and knowing a little bit about how Oblivion works, I believe there would be ways of doing this with OBSE at least.
That said, in response to the OP's question, no, I don't think a mod like this exists. It really should, though.
In theory, wouldn't just artificially giving you a huge bounty be close enough? I mean if you were a known evil warlord I doubt the beggars would run up and start attacking you, it'd really be the guards. Maybe some way of scaring people away OR making them aggressive (based on their Responsibility, Aggressiveness, a level difference) would be cool, although I assume much harder to implement.
CC