Are there any websites that collectively track one computer based on its IP address alone? Browser extensions such as Ad block plus, Do Not Track Plus and Ghostery modify the client side script but is it not conceivable that a server would just associate your IP address with the page you requested and share it with some network? For example if you search for a suit on a site hosted by server A and server A passes along your search information and IP to other servers in its tracking network, such as server B, then you go to a page hosted by server B and you start seeing targeted advertisements for suits. Even with scripts completely disabled this wouldn't be prevented against, is there any way to prevent against this? Is this scenario, or any similar, happening?
It is most likely that some ad network uses this method. To be honest I don't know, but I'm going to answer your second question.
How can they be prevented?
1) Change your IP: You can use a vpn or a proxy or TOR to change your ip. But you have to trust your data with the VPN service provider or host.
2) Confuse them: You can confuse them with an automated bot that browses random pages of the sites that use the ad network, giving them false information about your interests.