I noticed there are lots of them, and they only appear on AnandTech. Traffic is shown as going both directions. Yes, banner ad but it appears to be more than that. Two of them in particular seem to slow everything to a crawl, network.realmedia.com and ad.uk.doubleclick.net. I filtered out these "ads" using my firewall and now moving around AnandTech has become much speeder. I get the feeling they're sending info back to the mothership.