(Like a ɡood book, not a cool cartoon.)
Erowid: Documenting Psycoactive Substances
Computational Origami (youtube)
Psyop tactics the bad guys use
IMSLP - classical sheet music in the public domain (i.e. free)
Archive.org and the Wayback Machine
Amoeba Records - What's In My Bag (youtube)
my all-time favorite Lindy Hop
Orisinal - Ferry Halim - Bugs (simple, sweet online game)
Indigo Girls bootlegs and other stuff
Christopher Alexander, author of The Timeless Way of Building, one of the most important books ever written about the effect of the built environment on the well-being of the individual and the community.
Radio Garden listen to radio live all over the world
Shazam - it will tell you what song is playing around you (also available as browser extension - SO GREAT!
Windy.com - really cool global interactive weather map
another cool satellite weather map - Earth Nullschool