Neat things I've 'Stumbled Upon'

Music tools:
http://seaquence.org/
http://tonematrix.audiotool.com/  (simpler)

Games:
www.phoboslab.org/ztype/   Typing
flashflashrevolution.com     Rhythm game/ "DDR on the internet"

awesomeshityoucanbuy.com

http://meowmania.jqln.org/