It could be that GoDaddy are adding their own information to each page they serve (I don't know), but given the amount of adverts and links on your site I'd say GoDaddy is the LEAST LIKELY source.
Yup... word of advice. Godaddy is awesome at handling your domains. Their control pannel for DNS is great, as is their purchasing system and renewal mechanism. However... NEVER ever ever get shared hosting from them. They aren't technical enough to fix problems and they're not technical enough to setup hosted environments properly. The one exception to this is if you get a dedicated server from them. You get what you pay for, but in these cases YOU are responsible for the server so they are really just giving you a box somewhere in their data center.
In general, you should try and keep hosting separate from domain registration as others have suggested. There are literally hundreds of web hosts out there who offer hosting at either the same or lower rates than Goaddy's with much more resources along with responsive and helpful customer support and reliable servers.