Some yarn bombing blogs

http://purlinterrupted.co.uk/2009/07/13/london-graffiti-knitting-confessional/
http://jafagirls.wordpress.com/
http://knitthecity.com/
http://www.magdasayeg.com/home.html
http://www.skiffvintageknittingpatterns.co.uk/2009/09/graffiti-knitting/