Take me to your leader
Last night some show on CNN was on in the background and they were talking about Roswell and whether aliens really did land or not. Of course, I don't believe for a minute that there were any - no one could keep that big a secret for this long.
At the same time I was reminded of that unbelievably bad (and not nearly as enjoyable as I had hoped) CBS movie that was on a few weeks ago about a hurricane over Lake Michigan colliding with a whopping set of tornadoes. It was weirdly comforting to watch large scale property damage and loss of life and know that it's just weather (assuming you suspend all meterological disbelief ever), e.g. something you can't cause, prevent or stop before it's done. Plus, people absolutely must cooperate in really bad weather (even the real kind) in order for anyone to survive. Makes you feel all warm and fuzzy.
So, what would be incredibly cool would be some event that combines the excitement of weather and the cooperative behavior it induces, but without the property damage or loss of life. Or in other words, friendly (but powerful enough to protect themselves from the inevitable attempts to kill them first) aliens *need* to land. I mean, it would certainly be exciting and there's nothing like a new lifeform to bring people together...