Mark Enemies in Battlefield 3
I posted this on Twitter, but I felt it warranted it's own post. If you're playing Battlefield 3 this weekend and you're playing online, help out your team by marking the enemies when you see them. It's extremely simple and will allow your teammates to see the enemies on the mini map so they know where to attack. You can even tag vehicles.
To tag or mark players on the PC use the 'Q' button. On the Xbox 360 use the "back" button, which is the button next to the "Xbox Dashboard Button", the one that isn't the start button. On the PS3... I'm honestly not sure, maybe select? But seriously, if you want to play this game correctly and you want to win, there's no reason not to help out your entire team by marking/tagging the enemy on the map so they can die faster.