On one hand people are - and have been for years, really - complaining that there's way too much ganking going on; whether that's them being killed by people of their own level, or whether it's them being killed by higher levels, we can never know. They can always cry they got "ganked", even if it was just a death in a fair fight.
On the other hand people are - and have been for years, really - complaining that there's not enough world PvP going on; people fly off on their flying mounts or sit in towns.
Well, here's an incentive to solve both problems:
Make the first honorable kill of the day, outside of arenas and battlegrounds and limited by the level of the enemy; 90's get it from 90's, other people get it from 2-5 levels lower at the most, award you a [Bag of Goodies], much like finishing an instance. This bag can then drop all kinds of fun things, for example gold (of course), level-appropriate rare items, worst current PvP tier items, toys, pets, mounts even. Make the bag BoA too, so you don't necessarily have to go out there on your suckiest character, but you can do it on the one you feel most comfortable with, and yet if you want more bags a day, you can switch characters and continue fighting.
This way 90's would venture out into the world to find other 90's (gankers being a very good target), lowbies would have some unexpected air support from the higher-ups, and the zones would be much more active. Yet people wouldn't spend all their time out there since it would be a daily drop.
People on PvE realms could go out there with their flags active looking for trouble, perhaps even get crossrealmed with PvP realms if they do have their flags active. Or they could stick to PvE and be safe.
Giving honor from world PvP never did anyone any good. It didn't work as an incentive and you never got enough to actually start farming. Perhaps if you could get something more tangible people might have a reason to move their asses to the world.
Now, if you add, on top of all of this, some PvP hotspots into different zones out there, the defense of which might even give you a second, third, fourth and so on, bag of goodies the same day, by doing something like defending/attacking the area for X minutes or whatever, you might actually get some nice wars going on, and possibly all the action would move to those smaller areas, and higher-ups would leave the lowbies alone a bit more.
The way I've seen it, gankers aren't usually people in full top-tier PvP gear with high ratings and lots of PvP skill. Said gankers might feel a bit more intimidated about attacking people if there was the constant threat of people suddenly jumping on them and destroying them on the spot.
The contents of the bag of goodies can of course be debated, and I'm sure a lot of people out there who aren't interested in fighting other players would feel pretty pissed off if there was a system where killing other players could give you all kinds of cool stuff. Then again, Mists of Pandaria was supposed to promote PvP. Well, here's a way.