Here is a collection of my current favorite links:

MUSIC:
http://www.allmusic.com (It really is ALL Music!)
http://www.archive.org/details/etree (FREE & LEGAL Music!)

TEACHING:
http://www.ratemyteachers.com (Are you on here?)
http://www.learner.org (FREE streaming videos)

SCIENCE:
http://space.jpl.nasa.gov/ (Visit Space)
http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html (Powers of 10)
http://hubblesite.org/gallery/ (Screensavers-R-Us)
http://www.mos.org/sln/SEM/ (Cool Shots)

TECH:
http://epic.makingithappen.co.uk/ (The Future of Media?!?)
http://weblog.infoworld.com/udell/2005/01/22.html (Cool screencast of Wiki transformation)

HUMOR:
http://www.txt2pic.com (Make your own signs!)