My Brother-in-Law is in town and he wanted to play something online. After spending 10 minutes trying to figure it out- it turns out you can't play Modern Warfare Split Screen and online at the same time. :(

So, we ended up playing Halo 3 online/split screen. (We invited C3PX, but he preferred just to listen to some tunes. Loser.) And we ended up on the Rocket Race Double XP playlist. I'd never played that before and I actually really liked it. For those who don't know, it's very reminiscent of Mario Kart Double Dash- There are 4 teams of 2 and Rocket launchers are the only weapon and you get unlimited ammo. You race around on Mongooses (Mongeese?) where one person drives and the other shoots. Random checkpoints appear on the map and the goal is to get there before the other teams. If you can't get there before another team- shoot them with a rocket and see if that changes your options!

I think it's probably the most enjoyable when you're sharing a screen with your teammate- but maybe it's fun purely online too- I don't know.