Age of Conan, at least according to today's dev update letter. The Hyborian Halloween event will run through November 12th, but chances are you'll be more interested in Funcom's plans for the game going forward. Chief among those plans is the achievement system slated for update 4.5.
Funcom says you'll collect achievements for everything from leveling to PvP stats and minigames to dungeon and raid completion. There's also a lore journal and a panorama mechanic that provides "a camera path, an achievement, and experience" each time you find one.
Don't forget about the pit of trials, a level 80 arena designed with both PvEers and PvPers in mind.