browser extentions

need browser extentions for chrome and firefox to put advertisement on selected websites and webpages.. idea is simple just if i want to put advertisement on [login to view URL] i will add on my server and those who have my extentions installed will see my advertisement on their google webpage.. need extention to be controll by some server so i can update advertisement whenever i want.. if silent installation of extention is possible then it will be really good.. must work on latest versions