Tag, Tag and Tag

RFC4151 is about tag.

http://laurie.informatik.uni-bremen.de/kbthesis/
http://cloudalicio.us/

http://www.corante.com/om/archives/032470.html
http://www.threadwatch.org/node/1206
http://www.corante.com


Social Bookmarking Tools(I)
Social Bookimarking Tools(II)

http://www.connotea.org/
http://www.citeulike.org/

http://www.colr.org/

http://www.getluky.net/freetag/

http://sourceforge.net/projects/scuttle/
http://www.tecknik.net/poke/post.php/80
http://scuttle.org/