Personally, I think that moot has done more to further the internet and modern culture than almost anybody out there--and that includes Reddit (and arguably Something Awful, but nobody wants to waste tenbux anyways).

4chan has provided and continues to provide a raw visage of how people behave given total anonymity. It has a wide ecosystem of boards and interests, and in the last six years has certainly left everyone who's lurked there a changed person.

Remember: near all of the bullshit memery, the image macros, the open discussion, the invasions, all started with 4chan.

If anybody else is successful, it's probably because they can point to the awesome parts of 4chan and say "We want to build that, but friendlier, better moderated, and less anonymous". It was a proof-of-concept, and a brilliant one.

It'll probably die off in the next five years, but it's done some amazing things and brought a lot of people together.