I started to work at AdRoll a few months ago and it got me to think of different ways to use retargeting, while remembering about this story.

For example, if you're looking for a job as a designer or an engineer (or whatever else), you're likely to have a site to show some of your projects. Potential recruiters that end up visiting your site can then be advertised to specifically.

I was also thinking of blogs: you can probably recapture an audience when you write a new post. I.e. one of your posts gets popular on Hacker News, but people won't necessarily start following you or subscribing, but you could advertise for your new posts later.

I'm surprised not to have heard of another story similar to that Google one since then, but there is potential if you think about it.

edit: actually, I remember reading about a guy who had targeted his significant other using a Facebook ad for some purpose (maybe a proposal?).