Blogger Pop-Ups?

I've been testing out various new Blogger features over the past couple of days and decided to finally try out the Blog This! thing that's included with the excellent Google toolbar. It worked just great, but oddly, when I opened up the blog (not this one, my R&D blog where I do my experiments first so as not to screw up this one), the Google toolbar informed me that it was blocking a pop-up. I unblocked the pop-up to see what it was and it was a typical stupid ad telling me I'd won something. But why was it on my blog?

I rarely see pop-ups anymore because I use Firefox and on IE I have the pop-up blocker that's built into the aforementioned Google toolbar.

So what's the deal? Does Blogger now feature pop-ups or was it somehow connected to the Blog This! thingy? Has anyone else seen pop-ups on Blogger sites, or am I just going insane?

My system doesn't have any spyware on it either, so don't suggest that as the culprit.

Update: I'm not sure, but this pop-up thing may have something to do with Bravenet. I've got a Bravenet hit counter on the R&D blog. If it's not that, I'm fresh out of ideas.