It's maybe a bit off-topic, but I found it an interesting find that DJs can try out theirselves. I stumbled upon it by accident when mistakingly mixing the same track twice.
Song to use:
Moonbeam & Tyler Michaud Feat. Fisher - Love Never Dies (Original Mix)
How to get the effect:
Play the track twice (overlapsing) and start both at the same time (exact) and you will become a kind of flange effect on the song without using effects... Then play with the volume of one of the two channels ...
Pretty cool heh? :D
(first part is a piece of the original, second part is same piece but track played twice)
BTW: Do you think DJs should use effects like flange (or other) while mixing? Personally I'd say NO. But let's hear it...