I barely noticed today a notification that a pop-up from this site had been blocked, and found that it was a survey.
The only reason I looked into this was because I hadn't known Wrox to use pop-ups before.
IMHO, it's probably not a good idea to use a pop-up to catch a user's attention anymore, as many people have pop-up blockers. If I wanted to survey the people on my site I would probably put the survey (or an eye-catching link to it) in someplace where my users aren't used to seeing something, similar to what was done with the code downloads link. Adding another number to the blocked pop-up count probably isn't going to draw much attention :-)
My two cents,
-Snib -
http://www.snibworks.com
Where will you be in 100 years?