"For all the cobwebs I've seen in my life, I've never seen a cob."

Regarding cobweb building spiders
http://www.cirrusimage.com/spider_cobweb_Enoplognatha_ovata.htm
http://www.cirrusimage.com/spider_cobweb_Steatoda.htm
http://www.cirrusimage.com/spider_cobweb_Theridion.htm