Off the top of my head, the Pipboy Readius/2500, and FO1 style laser weapons (if BGS insist on those boxy abominations they call laser rifles again).
http://www.nexusmods.com/newvegas/mods/58606/?
http://www.nexusmods.com/newvegas/mods/49524/?
http://www.nexusmods.com/newvegas/mods/48653/?
The first that comes to mind is the motorcycle mod.
What possible? The developers using player authored mods for a future game?
Most, if not all, of the new features in FONV were mods created for FO3.
Hopefully a survival experience is built into the game. I'd also like a grenade hotkey, a sprint button, and helmet visual effects. Other than that i think obsidian implemented all the cooler mod ideas from fallout 3 into nv
Project Beauty. You know the face/hair options will be minimal at best.