The percentage of users who report using pop-up or ad-blocking software increased from 26% in April 2003 to 69% in September 2004
Most Hated Advertising - Jakob Nielsen reporting on research carried out into online advertising.
That’s a lot of pop-up blockers. Most of those will only be blocking pop-ups created at the onload and onunload events, they will permit popups created via onclick and onsubmit and also new windows launched via the target attribute. But some will be more aggressive pop-up blockers that block all pop-ups. I have Norton Internet Security installed and that falls into the latter category.
The new menace is DHTML effects that position a layer above a web page. It has all the same negative effects as a pop-up but is much harder to detect and block.