Hey there! While I love fanfilms, and you guys can point out some good ones (Chris Notarile has always been a favorite of mine), I wanted to point out an art form that I love, and that is the re-editing, and sometimes photoshopping, of existing footage to create a trailer for a nonexistent film.
One of my favorites of these of old was a Justice League fan trailer that was incredible, but I CANNOT find it online now to save my life. It was around, I believe, the time of Superman Returns, and it featured Routh and Bale as Superman and Batman, using additional footage of Bale from Equilibrium. It's footage of Wonder Woman came from some kind of South American TV commercial. It mixed footage of John Wesley Shipp's Flash with Ryan Reynolds to create it's Flash, while James Caviezel was their Green Lantern. It also used footage of a robot from Judge Dredd and a slo-mo explosion from Swordfish. The result was memorable. If anyone has memories of the same one, let me know!
And lets' talk about the best in both art forms!