Three things that I've found most useful and fun during the 23 Things course are:
1) Photo editing with BigHugeLabs http://bighugelabs.com/flickr/;
Podcasting which is subscribing to ones favorite podcast feed, ie: http://www.vinow.com/blog/, http://www.qualitytime-esl.com/spip.php?rubrique20 through the Bloglines website http://www.bloglines.com/myblogs and finally adding
YouTube http://ca.youtube.com/?utm_campaign=en&utm_source=en-ha-na-ca-bk&utm_medium=ha&utm_term=youtube, clips to my blog.
Please visit my blog site http://www.jascent23.blogspot.com/ to see my handy work.
2) My title search in Hammond wiki is music with a result of 5 titles, http://www.dairiki.org/HammondWiki/TitleSearch?auto_redirect=1&s=music
ex: SheetMusicSources had about 11 website links, http://www.burtnco.com/.