This is a very valuable project.
Here are some moments I think are worth noting.
1999 - 200416color.com accumulates 40,000 user-submitted animations. Who else remembers this?
They had an app for making animations, which could upload them to the site, which hosted them as gifs. Everything shared a 16 colour palette and a fixed resolution. Tons of amateur doodles, a few absolute gems, lots of disgusting and offensive cartoons, some interesting multi-part series and animated tile things (exploiting the listing pages' layout that showed animated thumbnails in a grid). Pre-Youtube crowd-sourced animations for the masses.
Then it unceremoniously shut down, deleted everyone's stuff, and
released a 'best of' DVD.
All proceeds go directly to the development of 16 Color's next version coming in 2005.
... yeah, that never happened. (Someone else should step in and make a spiritual successor.)
2008-2013(?)imageboard.net - another accumulation of user submissions, sadly lost to the ages.
Some pages are on the Wayback Machine. Not to be confused with a site like 4chan. It was basically a forum without text: threads with only images as replies to images. And not uploaded images, but ones drawn with the site's pixel-art-oriented Flash drawing tool, usually incrementally modified from the previous post. Fixed resolution, unlimited palette.
Largely anonymous, although users could make accounts. But it didn't show usernames--no text, remember!--just pixelly avatars.
Everything was posted with a share-alike Creative Commons license, and user-rated for quality and offensiveness.
Another site that could use a modern reboot.
2008Mozilla's Firefox 3 is released, with rendering behaviour that automatically anti-aliases zoomed images. Pixel art enthusiasts are pretty much the only people on Earth who complain about this change.
[1] [2]This is largely fixed later: current browsers including Firefox generally anti-alias images by default, but offer some
unofficial CSS features to allow site authors to switch it off and render fat pixels.
2010Apple releases the iPhone 4, with 'Retina display': 4 times the screen resolution density. Pixel art hit again with unwanted smooth-scaling rendering.
A few kinda negative points. Call it
History of the Downfall of Pixel Art 