BlockPop works by integrating directly with Internet Explorer, to stop popups before the windows even become visible. This means: no flashing, and no wasted bandwidth waiting for ads to download.
BlockPop block any annoying popup ads automatically. With its popup block engine, BlockPop can block 99% of all unsolicited popup ads and will never interfere with your normal navigation. BlockPop can block pop-up, pop-under, on load popups, on quit, after delay popups and even the most annoying popup ads will be blocked, which most other popup killer can't block. Requirements: Typical Win95 machine Operating system: Win95,Win98,WinME,WinNT 4.x,WinXP,Windows2000 Release notes: New Release
BlockPop 2.1 details 