Don't forget to look for this Arma Easter egg on Christmas!

On December 24th and 25th, you'll see Christmas trees in Arma 3 and Operation Flashpoint/Cold War Assault! You might have to search for them, but they can be found on Livonia in Arma 3, and they appear on every map (as far as I know) in OFP/CWA.

As a side note, I really enjoy just taking a step back to explore the scenic maps in every Arma game. The ambience is peaceful, and the Christmas trees make it even better.