MAG open beta client. The system's MMOFPS will be online until the 10th, when they take the game off the store and prep it for the official January 26th launch.
Beware you have room on your hard drive and time to leave your PS3 on to download, however, as you'll be looking forward to a 2 GB download. A headset is nice to have too, so you can communicate with your squadmates (they'll appreciate it,) but it's not required to play the game.
So this weekend enjoy conducting a war with 255 other people on the battlefield with you. Try not to get shot too much!