Ubisoft released a free Far Cry 3 app for iOS and Android: Far Cry 3 Outpost, which unlocks in-game content for multiplayer and co-op.
The app lets players decode encrypted data found in the game to unlock weapon mods and earn bonus XP to use in multiplayer. It also tracks the stats (time played, level, top weapons, awards, etc.) of both the player and her/his friends, and also allows players to view and customize their loadouts on the go.
Here’s the trailer that accompanied Ubisoft’s announcement: