Like skyline or what ever its called has one for getting on the green house in the middle
Pier 17 has one for swimming in the water.
Anyone know anymore?

um I have seen on youtube in singleplayer an easter egg. I don't know if it gives you anything I'm waiting on my copy in mail. But just search crysis 2 easter egg if you want to see it.

ah no. what im talking about acts like a challenge in multiplayer and they seem map specific.