4. Online Bounties
The "Run Like the Wind" achievement says, "survive for a day with a Bounty on your head", and here's the kicker - it's an online achievement. We already knew that GTA V was bringing Bounty Hunter missions into the single-player mix by way of Trevor, but it's also going online, meaning that you will be able to (somehow) place a bounty on a player's head - likely by way of their XBL/PSN username - and presumably invite other players to try their hardest to take them down, in return for a tasty monetary reward. Though we don't know how long a day will last in game time or how this achievement will specifically be earned - surely hiding offline for 24 hours isn't sufficient? - it sounds like it will add an addictive new dimension to gameplay, and ramp up the competitiveness.