No, you're thinking, not another thread on this! Well... I just sent this e-mail to someone and thought that I would post it here to see if I left anything important off the list.
<pre>There are two general modus operandi of pop-up blockers: those that stop
them unless you do something special, and those that allow them unless you
blacklist them. The former category makes you life MUCH simpler, but can
disable legitimate sites (until you figure out what's going wrong and add
them to the exception list). The latter category requires you to train them
to some extent, but leaves the control in your hands.

After reading some comments and suggestions, I think the choice is a matter
of taste: do you want the least annoying pop-up ads, or the least
behind-the-scenes interference with your browser?

Type 1: Block until told not to...

AdSubtract Pro - $30 / 30-day free trial
CNET Review:

Guard-IE - $30 / 20-day free trial
CNET Review:

Type 2: Block from your list...

NoAds - FREE

What I didn't note in my message was that AdSubtract actually blocks ads in the web pages themselves, and Guard-IE includes some firewall-like features. These might help someone in choosing between those two products.

I also didn't discuss spyware, which I think has been well addressed in threads on Ad-aware.