This fan-made trailer has been around since 2007, and I am aware that alot of CBM's members have seen it, I am simply posting it because I think it is really well done. I only saw it for the first time a few days ago, so it is likely that there many others who have not seen it. If you have seen it, then watch it again because it is worth it.
Here is the basic idea behind the trailer: Superman must unite the world's greatest superheroes to form the JLA in order to save the world from an alien invasion.