Fighting Pop-Unders
"Now, as a spate of ill-conceived Web ventures are failing, some Internet entrepreneurs, in desperation, have turned to pop-unders, an ad technology originally conceived by the online pornography industry. The law may allow it, but the good news is that Web users can fight back.
The key to blocking most pop-under (and 'up') ads, it appears, is to disable JavaScript on your Web browser. Doing this universally, however, prevents certain types of sites – such as online banking – from performing properly. The trick is to disable JavaScript selectively on a site-by-site basis. It was David Lerner, proprietor of Tekserve, the New York City Apple Computer specialist, that helped me find a realistic solution to block the ads when he passed on this URL. In it, I found an answer that can reduce the ad plague for both Mac and Windows users.
In a nutshell, using browser preferences creates a 'security zone' around offending sites. Within this zone, you can selectively disable JavaScript for the specific sites whose ads you wish to block. On Internet Explorer 5.0 for Macintosh, I went to 'Preferences,' selected 'Security Zones,' and then selected 'Restricted Sites Zone.' I then entered the custom settings panel and disabled scripting, plug-ins and Active X controls. Then I selected 'Add Sites' and listed the URLs of those sites that send me the ads.
Bingo, it worked."