These cookies are used by doubleclick.com and valueclick.com to target you with specific advertising when you go to a site which contains their adverts. See
http://www.cookiecentral.com/content.phtml?area=4&id=10 for more info.
From the lavasoft.de website :
Are cookies dangerous?
A: The answer is no.
A cookie is a pure textfile, and can never contain any exe files or viruses.
Only the webserver that has created the cookie can get it in return. It is impossible for anybody else that does not have actual access to your computer to snoop around among your cookies and therefore see which sites you have visited.
However, some cookies do assign you a unique identifier, that means you will be identified when you return to the website. Some personally (i.e. Doubleclick) - some not.