Automatic recharging enchanted weapons from Morrowind, this doesn't mean we get the weapons from morrowind in Oblivion, but the enchanting system.
In Oblivion if you have an enchanted weapon, you can use it for a while, but then it's finished, and you will have to recharge it with a soul gem. Now I hate this. I liked the Morrowind version better, that enchanted weapons will recharge itself.
So a nice mod would be self-recharging enchanted weapons.