I used to really like this site when I was in middle school, but it's current incarnation is just a shade of what made it liked by so many people. Although the original site code remains, it's covered by this weird facade of Flash, Java, and PHP adds that makes the site almost unusable. They also removed most of the original UI; site navigation is now a total pain in the ass and almost impossible.
A bit of research revealed that Neopets had been bought out by MTV in 2007 for 160 million. It's not surprising then that they're turning it into an advertising farm.
World of Warcraft
Golden Age: 2004-2006
Decline: Isn't really in decline, but slowly is losing why I liked it.
When this game came out, it was freaking amazing. I played myself for almost 3 years, but unlike neopets it's still mostly easy to use. What happened here was, the constant influx of people eventually replaced the social group that played the game. Gone were the nice variety of people from all walks of life you'd run into, but instead WoW became a mainstream thing that everyone and their grandma played. This actually enriched the game, but what's killing it is the consistant 'dumbing down' that's happening from Blizzard's attempt to please everyone at the same time. The result is a game that, although still fun; (I can still play a Paladin to this day!) just doesn't have what it used to in gameplay and feels kinda mindless.
There's also some level of commercialization, not unlike neopets. Trading Cards, Figurines, Pins, etc.
2004-2006 or so
This site went from being pretty awesome and entertaining on a consistent basis, and then literally overnight with a format change started going downhill. Granted, I LOVE orange, but the site pretty much has been losing users ever since then. That and the lack of original user generated content has pretty much meant this site is kinda dead.
Oh, and fyrestorm stopped making YTMND soundtracks.
Other sites that have gone downhill:
- The general OEC community. Save for a few sites like Veritas that thrive due to other reasons, most are shades of what they used to be.
- Limewire. What used to be a great p2p tool is now just a good way for the RIAA to find you. Bittorrent is your friend.
-4chan. Not much to say here, but take a look at it. It's REALLY not what it used to be.
I think it was in Pirates of the Caribbean they said "The world isn't getting smaller, there's just less in it". The passing of time sucks =(