There are plenty of browser extensions around which promise to block a particular type of object: cookies, scripts, ads and so on. HTTP Switchboard is a Chrome extension which goes further, allowing you to selectively forbid or allow any type of request, and so can block just about anything you like.
To get started, install the extension, then point Chrome at a URL where you know there are plenty of ads, scripts and more. Plugins and frames are blocked by default, so you should immediately find the site is faster and more lightweight. Click the HTTP Switchboard icon and you'll also get a detailed report on everything your page is trying to access, and their original domains (3 scripts from "tracking.com", say), useful just to help you understand what a site is doing.
If the report shows cookies, scripts, images and more from "annoying-adverts.com" (for example), then you might decide you want to block these in future, and it's surprisingly easy. Just click "annoying-adverts.com" so that it turns red, click the padlock icon above it, and you're done; HTTP Switchboard has blocked that domain and you won't see any content from it in future.
You're not restricted to blocking sites, though. It's also possible to block a particular content type - images, say - just by clicking that column in the HTTP Switchboard grid. Or you can block specific content from a particular domain by selecting the relevant grid cell.
There are some potential complications, of course. As with any similar tool, it takes time to understand what you need to allow on a site to make it work. HTTP Switchboard does its best to help, though, and if you'd like to take more control over what Chrome is doing then it could be a very good choice.
Closed as fixed:
•xmlhttprequest = xhr