I've noticed that there are some popups, here and there, that make it by Google's popup blocker. They're usually launched by a javascript in a funky manner.
A google for Adznoodle brought up nothing- can you check the source on that?
When you run your spyware programs, have you updated the definitions for them? I just went to delta, got no popups after 5 minutes, google didn't block them either- that makes me think spyware/BHO adware/etc.
I recommend Spybot S&D 1.3, and Adaware. Note that S&D appears to not be updating 1.2 anymore- so you may wish to upgrade S&D if you haven't. Other spyware programs I approach with caution- I've seen several recently that are spyware/adware detectors, save detecting themselves and THEY'RE the spyware/adware. And sometimes not detecting "marketing partners". Grrr.
When you go to Delta.com, try this: Click where it says #### blocked, and it'll say "popups enabled." Then click it to blocking again. This might help some. you can also go into the google toolbar properties and disable/re-enable the google popup blocker.
Hope this helps some, let us know about the spyware definition updates, what programs you're using, what the ad sources are, and any particular offending websites.