I am gonna basically steal this idea from Seasonal Diablo 3.
So basically what I think would be interesting is seasonal PVP, everyone on any server with level 80 can participate, seasonal character is optional. It would copy your main character professions and you would choose your starting spec and be given the crafted level 78 starting gear with basic pvp trinket. This is to give everyone a fair starting point. Unlike how Blackrock currently works, where they get free furious gear vs people on Icecrown or Lorderon in pve/or crafted PVE gear..
PVE items are not allowed in Seasonal content such as Arena or BGs, they can be used in WG and in WPVP. At the end of the season there would be some type of reward system for different categories, top healers over the season, top dpsers, top defenders, top flag carriers, and of course top arena teams. There might be rewards such as cosmetics that could carry over through seasons or special titles etc.
Each season lasts maybe 6 months and after the season ends all gear obtained is wiped. The title/reward is account bound, seasonal characters can not be sold or traded. When a new season starts everyone is back to level 78 starting gear, or they can participate in non-seasonal pvp where anything goes. Kinda like how in D3 you can choose to do seasonal or non-seasonal. It would also be nice to see win/losses for all seasons pvp content say a person goes to WSG WIN/LOSS/AFK. If a person has a high number of AFK's they would be removed from the season.
I think it would spice up the PVP scene and be a way to provide some balance for people who like to pvp. I'm sure there would be some other awesome ideas to make this even better.

