Yarn bombing is a type of street art that uses knitted or crocheted yarn. The most seen pieces are trees covered with crocheted yarn. I have seen two in Munich (Germany) and another one in Oviedo (Spain).
I think it could be a great way to recycle yarn or fibre!!
Yarn bombing in Klenze Street in Munich (Germany)
Yarn bombing in Asturias Street, Oviedo (Spain)