I first learned about newgrounds sometime after 06/24/2001 but before 12/30/01. I know it was after 6/24/2001 because the first thing I saw was ...
I found a link to it on a forum that I was lurking around on. It was my first taste of newgrounds and it was up beat, funny, and slightly disturbing and it got me hooked. The site was a lot rougher in those days; the highest rated flash had a score of like three and a half.
What I enjoyed the most about the site was how you never had any idea what you would stumble on. High School of the Apes, Disorderly, Kong, Eskimo Bob, Headache, Xiao Xiao No. 3 to name few. They were funny, they were serious, they were violent; there was anything you could want.
The biggest problem that the site has is that is pretty hard to find good content that's been on the site for a while. The search function is working better then it has in the past but it still isn't that great. Things like letting you sort your search results by date, author, score, views, stuff like that would help. Being able to do the same within the Games, Movies, Collections, and Series pages could also be beneficial. Those pages also have historically suffered from slow updating, it's gotten a lot better though, with so much on the front page, a lot makes it into the collections but I still suspect more could be done.
I'd like to see the blam animation back, the save one was too long but another short little animation would be cool. But what I really miss is the Assassin page. It used to be the site's flagship but has fallen in to the shadows over the years. It's no one's fault though, the users have moved away from making those types of games.