More crafting options including the weopons already mentioned would be nice, something to make the survival skill more worthwhile as well. The treasure could be gaining access to a hidden underground city (same scale as oblivion settlemetns or Shivering Ilse) which will again include a new range of traders (not just one jack of all trades serving a whole city), this will include side missions as well with the end outcome of these missions including armor or weopons depending on that trader or individual.
Other ideas:
Plastic surgery (followed by a trip to the Strip to get banned again.....)
Access to an amo press
Sally's homing becon from FO3.... beam on up and get ready for more interstellar warfare!
Special boots that allow you to walk through invisible barriers.
Mods for armor.
New/different implants. I'm also thinking cybernetics which can be seen in 3rd person view, perhpas along the same lines as Rex (though I'd want to keep the brain where it is thanks!).
One or two perks from the normal list, or perhaps choose from a much shorter 'prize perk' list. Could even be a load of skill points, either automatically assigned to skills or the player could choose how to distribute the points like normal.
I doubt however any of the above will ever be considered......