Ever-Growing List of Websites

Flash:
http://www.newgrounds.com/ - "the original - and still the largest - Flash portal on the web"
http://www.armorbot.com/ - highscores system
http://www.tutorialized.com/ - tutorials
http://www.flashkit.com/ - tutorials, SFX, sound loops
http://tsgk.captainn.net/ - sprites (aka. "The Shyguy Kingdom")
http://www.vgmusic.com/ - MIDI game music

Games:
http://fretsonfire.sourceforge.net/ - FOF woot!

Music:
http://www.ultimate-guitar.com/ - guitar tabs
http://guitarpatches.haax.se/ - guitar effects processors patches

Videos:
http://www.newgrounds.com/portal/view/458203 - RUN!
http://fu5ion.newgrounds.com/ - My animations and games
http://uk.youtube.com/watch?v=vLamuyCb3IA&feature=related - Brawlgasm!
http://www.youtube.com/watch?v=JaO3LA1nBjo&feature=related - How to tie your shoes in under 2 seconds

Awesome:
http://www.lucidmovement.com/ - slowmotion videos