I'd love to have a mod where your hair and facial hair grows over a realistic period of time before you need to cut/shave it. For example: After 2 in-game days clean shaven turns into light stubble, and 2 more days after that it evolves into thick stubble, which later turns into a light beard, and after a month turns into a full beard. The same thing could be done with hair, where a logical chain of hairstyles could be selected ranging from short to long, and the player's hairstyle would progress every month unless they decided to cut it/had it cut. The player would have to be seated in order to shave or cut his own hair, which would add a lot to immersion, having to go to an inn/your home and shave every other day. You could make a razor and/or scissors which the player could use to trim his hair down to the next regressive level, or add a skill which allowed the player to do it as long as he had said razor/scissors or even a dagger. I think it would add a lot of fun and immersion to the game. :)