The easiest way and probebly most effective way to get rid of pop-ups is changing internet browser. nowadays every browser has some pop-up blocker build into it or you can download one for your browser...BUT...the more a certain program is used the more likely it is, that people who want you to see that pop-up, will figure a way to avoid being blocked by the pop-up blockers.
since at this moment still the majority of the people use Internet Explorer and lots of them use google toolbar, msn toolbar, yahoo toolbar and several other usual suspects to block pop-ups, its most likely that these will also be the first to fail to actually block a pop-up.
however, if you switch to a not very well known pop-up blocker, or even use an entire different browser, wich has its own unique pop-up blocker, its a lot less likely the site that gives the pop-up will be able to get around it. i personally use FireFox and i rarely have pop-ups (although, since firefox is getting more and more used, especially on certain sites there are gettin more and more pop-ups through
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Edit: typo's
btw: this also counts for lots of other programs like firewalls, or any other protection program....the more its used the more likely it is people want to crack it