Those who live by the sword... get shot by those who don't.
Campaign: Outskirts
Nothing like fighting aliens as you make your way through a 26th century African city.
Multiplayer: Coagulation
It's big, it's fun, it's epic. I have zero idea why anybody complains about a map being too big. The bigger the better, I say. I say: give us some Battlefield 2: MC-sized maps in Halo 3. I say Sandtrap will freaking rock.
I also love how vehicles play an integral part in this map.