The latest versions of Netscape and Mozilla have a setting that disallows websites from opening new windows. Guess what popups are?
All you have to do is change your preferences so webpages aren't allowed to "open unrequested windows", and no more popups. In the latest version of Mozilla, this is under Advanced -- Scripts and Plugins. I think it used to be in Privacy and Security. YMMV.
Ciao,
Mort.