I'm seeing some user reports over the last week of malware possibly coming up from some of the plugrush popunders. I don't have specifics but I thought I'd put something up here so people can watch their own sites. The reports are that some of the popunders are trying to install malware ow Windows systems. That's all the info I have at the moment.
I notice that there have been other reports in the last few months:
http://www.mywot.com/en/scorecard/plugrush.com