Graphics

Gifcities
"The Geocities animated GIF search engine" Indexed thousands of gifs from Geocities pages.

Lunapic
Free web-based image editor. Has lots of options for cool effects and animations

Atom Smasher's Error Message Generator
Generate error messages from Windows 95/98 and XP

Freebackgrounds.com
Tiled 90's backgrounds

Buttonwall
88x31 button collection

Web Buttons
88x15 button collection

Free-blinkies.com (archive)
150x30 blinkie collection

Kurrus.net
Smiley graphics

Mazeguy
More smiley graphics

Ezgif.com
Free web-based gif editor

3dtextmaker
3d text gif maker

Cut photo into equal pieces
Exactly what it sounds like

Stickerclub2005.tumblr.com
Tumblr blog which posts scans of stickers!

Dither Me This
Dither and reduce the colors of images. REALLY usefull for retro aesthetics

Audio and Music

BeepBox
Free web-based chiptune creator

VGM Downloads
8000+ gigabytes of free-to-download videogame soundtracks

Lapfox Radio
Radio that plays Lapfox/Vulpvibe/Halley Labs music. Still up and running, even though no one uses it

BitView
"BitView is a faithful recreation of YouTube 2008. Nothing more, nothing less. "

Noclip
Explore your favorite videogame maps right in your browser

CatBox
File hosting service

W3Schools
The go-to resource for all things coding

Neocities Tutorial
Official Neocities HTML tutorial as a cute interactive comic

Super Famicom
Gameboy Color
Gameboy Advance
Nintendo 64
Gamecube
A bunch of console specific pages on the official Nintendo of Japan website. Untouched and intact.

Brian's SM64 Page
Brian's Super Mario 64 page

MarioCubeLite (archive)
Wayback directory of some dudes' WAD files (for Homebrewed Wiis)

CursorMania (archive)
Wayback directory of every single cursor from the now-dead site, CursorMania

iMood
Status updater thingy. You can place the code on your page and it'll update automatically

winXP.now
Browser VM of Windows XP

Windows 93
Parody of Windows 9x

404pagefound
"Active Vintage Websites, Old Webpages, and Web 1.0"

never-obsolete.tumblr.com
A very cool Tumblr blog dedicated to retro aesthetics and nostalgia