I'm not sure if anybody else finds them irritating but after recently installing Skype on a new computer, I found that it automatically adds call buttons to web pages when it thinks something is a phone number. It appears that this is a plug in that is installed for use with Firefox. It took me ages to find out where to turn it off but eventually I found it hiding in the tools menu under extensions. After disabling the Skype extension for Firefox those annoying buttons have gone and I am much happier.