John_B
Grasshopper
Please expand on what you are saying.
Ads networks regularly run Javascript code on webpages that actually reference code/objects on the ad networks' servers (it's how they track user page views, clicks, etc.). And some of those servers don't perform for s***.
When you read a post on SB, you aren't just loading pages from scubaboard.com, behind the scenes your web browser may also be accessing: connect.facebook.net, pagead2.googlesyndication.com, s.skimresources.com, www.google-analytics.com, and/or *.cloudfront.net (to name a few just on this page).
What elan is saying is that, depending on the web browser you use, it's possible to block communications to/from those sites, or to not load the placeholders that the ad images, facebook/twitter widgets, etc. use to display the ads or links in your web browser.