Everyone else has his most of my requests, but I'd like to add a few:

-Voice Recognition: when I yell "where's my f*ing flashlight" as a mouse invades my tent at 3:00am, I want the flashlight to reply by turning on
-If the above is not practical, maybe it could glow in the dark or have a very low wattage "night light" mode
-ability to recharge via USB when equipped with rechargeable batteries
-optional solar recharger
-multiple battery configurations (1 AAA internal, and an optional external cartridge for 2-4 AA or something)

the things others have mentioned: <1oz, red mode, variable brightness are all important too.