Why does the adbrite official site show up like this?? It's been a long time... also, some pages show up blank http://tinypic.com/view.php?pic=nxkzz4&s=5
Are you using Firefox? Maybe a plugin is preventing the site from loading all the content? Just a guess...
Plugins don't have mainly anything to do with the images not being displayed. The problem is most likely with the cookies or cache and disable functions in browser.
This problem occurs when you have adblock plus installed. Adblock seems to block adbrite's image servers thinking they are ads. Disable ABP for www.adbrite.com only and you should be fine.
Hm, I have AdBlock on Firefox and I can see the images without any problems, so not sure what's the problem people are having with the image not being displayed.