Full user review
"Superb at (specifically and only) blocking popups"
NoAds does an excellent job of blocking popups. Its database is already stocked to allow it to identify popular offenders, and you can easily tell it to add any popup that it missed. It's small, uses negligible resources, and works in the background.
CNET claims that it doesn't work for banner and Flash ads. If that's true, I haven't noticed.
I think that this is an ideal stand-alone popup blocker, and it's free. However, it does nothing else, so if you want additional functionality, it's not the product for you.