While the game does a pretty decent job in recreating the layout of Manhattan, it does get a few things wrong. I'd love to see a mod that changes the street signs that are in the wrong places or have the wrong names.
I'd love a mod that does one simple thing.. scales up all the encounters based on the number of companions that I currently have (using multi-follower mods). There are increased spawn mods of course but I'd like to see one that dynamically changes encounters based on how many companions I currently am using.