1) Nephalem Valor should not decay inside uber portals.
2) Killing a "purple" name monster should grant a stack of NV
3) Monster Power should increase the spawn rate of champions and rares, the higher the MP, the more challenging the mobs (and more opportunities to stack 5 nv).
***I think the above just about everyone will agree with. Now for the controversal ones.***
4) Uber bosses should give a considerable gold drop or a high number of item rolls to make it feel like there's still a chance of getting something decent if the organ didn't drop.
5) There should be profile statistics for amount of time nephalem valor was held, king of like time played but with nv, amount of ubers killed.
6) I recommend bringing back the original feel of ubers with the next event making the last 3 bosses (Diablo, Azmodan, Belial) a challenge and spawning unholy amounts of unholyness (skeletons) to cut down, and it should award an amulet similar to the ring, or materials to make one. Or perhaps for the expansion, making it Diablo, Azmodan, and whatever the act 5 boss is gonna be (Imperius?).
Something to think about. Thanks for reading.