Since events arnt on the svn yet i figured id make my own up.
helicopter crash site:
helicopter underground with a bloody combine ragdoll and a crate called "broken crate", played sound of canister crash then made a message saying a helicopter has crashed somewhere.
people found it pretty quick like!
What the crash looked like: https://dl.dropbox.com/u/52960971/2012-12-29_00002.jpg
Inside the crate: https://dl.dropbox.com/u/52960971/2012-12-29_00006.jpg
Message shown: https://dl.dropbox.com/u/52960971/2012-12-29_00007.jpg
Sound played: https://dl.dropbox.com/u/52960971/2012-12-29_00008.jpg
People found it all at once, non of them were either together: https://dl.dropbox.com/u/52960971/2012-12-29_00005.jpg
this could possibly be an actual event ingame. it worked out pretty well!