That's strange, because I was also using Chrome as my browser.. No worries; these ads are a small inconvenience.
Yeah, I should have been more specific. Chrome on Windows 7 64-bit, latest version of the browser. They make a Chrome browser of course for different OS's, and I'm posting this from the Nexus 7 using Chrome. On the Nexus, the blank spaces do appear.
One other thing I didn't mention for those who are interested. The ads you see will help you understand how your browsing habits are tracked. When you see an ad from a particular company or product you've visited, its because they placed a tracking mechanism (a cookie, browser helper object or applet usually) in your browser when you visited their site. The advertising uses these objects to generate what they consider targeted or relevant ads.
This raises some issues in the internet security arena, mainly privacy issues. One of the things that can help is to configure the browser to 'do not track'. It won't eliminate targeted ads, but it will reduce them. For Chrome users, you can find 'do not track' in Settings>Show Advanced Settings. In the privacy section, check the box starting with 'Send a Do Not Track Request'.
If you're using a Mac, the browser may not have these settings. But, you can also enable 'Incognito Mode', which will not keep your browsing history and does help.
Lastly, even if you take lots of precautions, you should assume that almost nothing you do online is private. The internet is in many ways the 'Wild Wild West'.